19 April 2017

More Information

Dr Brian Flynn, a senior lecturer in electronics and electrical engineering at the University of Edinburgh, visited the site in March 2017 and noted that the brick shed beside the cottage near the masts contains the remnants of a rather home-made looking equipment rack made of Dexion and hardboard held together with brass BA cheese-head screws. Both were favourite constructional materials in the old Electrical Engineering Department in the University when Brian himself was a student there from 1967 to 1971.  A 5-amp switched socket is attached to the rack with some wiring. There are numerous cables that look like signal cables.

Brian was aware that the masts were erected in the early 1960s for a radio propagation experiment.  He also recalls several of the Department’s technicians telling of some of the scary work they performed on the masts.

None of Dr Muggleton’s published papers make reference to his work with the Boghall riometer, and no written record of its use has been found within the University, so it is not known if any significant results were obtained. Brian has also attempted to trace the project report compiled by Bruce Taylor, but it appears not to have survived.   

20 March 2017

A Full Explanation

Dr Bruce Gillies Taylor has supplied a detailed account which now fully explains the purpose of the Boghall installation:

The antenna was used for Riometer (Relative Ionospheric Opacity Meter) measurements at 30 MHz during the IQSY. 1 The horizontal wires strung between the vertical poles formed one plane of a corner reflector, while the other plane was formed by the sloping terrain. The centreline of the antenna was directed at the north celestial pole, so that the antenna continued to receive radiation from the same area as the earth rotated on its axis. I wasn't involved in the construction of the antenna, but during the summer of 1964 I did go out there at Dr Muggleton's request to make impedance measurements at the receiver end of the feedline, and I installed a stub to obtain a correct match. The 30 MHz receiver, by the way, was built by the electrical engineering lab technician, the late Harry Matthews.

The reason that I remember something about the antenna is that during 1963/1964 I researched different noise sources for calibrating the Riometer, and built an automatic calibrator using a semiconductor noise source that was installed with the receiver in the hut at Boghall. I've attached a photo of the calibrator. This work was the "Honours Special Project" that was part of my final year undergraduate study, and there is more information about the antenna, the galactic noise sources that it received, etc, in the electrical engineering department report "Calibration of a 30 Mc/s Riometer", Ref. H.S.P./22, 25 May 1964.

Unfortunately I don't have a copy of this report, because only one typed and one carbon copy of the text were made. I submitted the typed one to Prof Farvis, and gave the carbon copies to the department's photographer, who had kindly taken many photos for me and wished to submit a copy of the report to a photographic body for the award of some kind of certificate. These HSP reports were not held in the library, but were kept personally by Prof Farvis in a cupboard in his top floor office.

The measurements at Boghall were recorded on punched paper tape, and at a later stage I wrote an ATLAS computer programme to reformat them. Dr Muggleton did indeed carry out ionospheric research on the Monte Carlo - Edinburgh path, but this work was done in the 40-metre broadcast band and not at Boghall. 

Yes, the antenna was erected specifically for the IQSY Riometer, and wasn't used for any military or HF communication applications.

I don't recall whether the dipole within the corner reflector was supported by two additional wooden poles, or just suspended between the guy wires. The antenna had a 3 dB beamwidth of about 30 deg in both E and H planes and a 10 dB beamwidth of about 65 deg. The H plane sidelobes were 20 dB down at +-70 deg, and other sidelobes were more than 30 dB down.

The sidelobes could be ignored in the calculation of the background level, since at no part of the sky in the northern hemisphere is the level more than 3 dB greater than at the celestial north pole, but had to be considered when evaluating the contribution due to the intense discrete sources, such as the sun. From about April to August, the sun passed through the upper H plane sidelobe daily around noon. (This lobe pointed south at an elevation of about 50 deg). However, during the quiet sun period 1964-65 I calculated that the contribution from the sun would be negligible.

The steelwork just downhill from the masts supported the wooden hut that contained the receiver and the noise generator calibrator, and it was supplied with AC mains power by the overhead lines. The noise generator ran from a regulated 180v DC supply. A separate 36v DC supply powered a Londex coax antenna switch, and a Ledex solenoid driving the rotary attenuator, via a control box containing dropping resistors. During a calibration cycle, the input to the receiver was automatically switched from the antenna to the noise generator, and the attenuator then rotated in steps to provide signals at +10dB, +5dB, 0dB, -5dB and -10dB relative to the expected quiet sun level.

The clock signals that triggered the calibration cycles at intervals were transmitted to the receiver hut by overhead lines. After the system had been installed at Boghall, I was asked to go to the site because it was reported that the calibration switching was not functioning reliably. I discovered that the cause was that Harry Matthews hadn't been aware that these lines were carrying pulses rather than just DC, and he had connected large capacitors from the lines to ground as precautionary surge protection!

 (Information supplied in  two e-mails.  Bruce was contacted at the suggestion of Bill Hume)

1. IQSY =
International Quiet Sun Year, the name given to a series of coordinated Sun-related observational programs performed in 1964 and 1965

19 March 2017

Ionospheric Research?

Bill Hume, who was an undergraduate at the University of Edinburgh from 1960 to 1964, associates the masts with Dr L M Muggleton, on the Electrical staff of the Engineering Department.   Bill says that he seems to remember it being mentioned that the angle of the slope of the hill complemented the vertical aerial.  He was not close to the aerial at any time and he is unable to supply any further description of it.   
(Bill replied to an appeal for information placed in RadCom, the members' magazine of the Radio Society of Great Britain) 

Further enquiry reveals that Dr Muggleton was noted for his research into radio wave propagation via the ionosphere.  He held his position at Edinburgh from 1961 to 1973. 1   He also provided technical advice to the evangelical broadcasting organisation Trans World Radio, who established a short-wave transmitting facility at Monte Carlo in Monaco in 1960. 2, 3   An abstract of one of Dr Muggleton’s research papers published in 1966 refers to an investigation of the Monte Carlo-Edinburgh ionospheric path. 4  Dr Muggleton  was born in South Africa, and in an earlier PhD thesis submitted to the University of Cape Town he mentions his observations on radio reception at a site in Southern Rhodesia (now Zimbabwe) of short wave transmissions beamed by the BBC to Africa. 5   Dr Muggleton’s connection with South Africa might explain the origin of the story about the use of the Boghall site to receive signals from South Africa. 

21 February 2017

The Mystery Solved

A former Post Office/BT employee, Jim Crockett, has provided the following explanation of the purpose of the Boghall Installation:

"Back in 1964, when I was a GPO Youth in Training (engineering apprentice) I spent a period of time with the Edinburgh Survey Officer (based at Hopetoun Street). One of the tasks we took on, was to survey the Boghall site for pole erection. Back in those days, the GPO had a high level of community spirit, and offered to erect the poles for Edinburgh University to allow them to set up a tuned receiving aerial, for an early design of radio telescope. The site was selected as it was well shielded from City electrical pollution. If I remember correctly, the poles were recovered from an old GPO HF radio site, transported to Boghall, erected, and handed over to the University for their own use - probably all free of charge. How they were fed, I don’t know but suspect they were used to feed a radio receiver at a remote University location."

Jim Crockett responded to my request for information posted on the website of Bill Rees www.btpensionersreconnect.co.uk  -  Thanks to both.

Any further details about the aerial would be welcome.  


06 December 2016

Boghall Radio Masts

I have long been intrigued by a derelict structure that appears to be the remains of an unusual radio aerial installation on the lower slope on the south side of Caerketton Hill at Boghall on the A702 Biggar Road just south of Edinburgh.1

There are two wooden masts fitted with climbing rungs.  The masts are some 30 metres tall and are about 30 metres apart.  Each mast is formed by two wooden poles cut diagonally at the join and held together with bolts and metal bands around the mast. The masts lie on a line running exactly east-west.2  They are guyed by steel cables, with a steel cable running between the mast tops.  The masts support a number of horizontal wires of uninsulated copper or copper alloy, about 2.3mm in diameter.  When I first noticed the masts in 1971 many of the wires were intact.  Only five of these wires now remain, but it is clear from the residual broken ends of wire attached to the masts that a pattern of evenly spaced wires extended from just below the top of the masts downwards to within approximately 2 metres of the ground. The wires are not insulated from the masts.  On the west mast the wires are wrapped around the mast and secured with staples.  On the east mast the wires are attached with hooks and tension adjusters.  At the west mast the wires have been linked by a wire running downwards which was until some years ago hanging below the lowest remaining horizontal wire.

In front of the masts, about 10 metres downhill and equidistant from them, three steel frames are set in concrete into the ground.  This steelwork occupies an area measuring about 4.5m x 2.3m and looks as if it could have supported a small structure or container.

About 15 years ago I noticed redundant telegraph poles leading towards the site.  I don't recall how many poles I saw then.  The insulators on these poles would have carried at least four circuits using open copper conductors.  Two of these poles remain, and they are now lying on the ground, a result of decay or possibly demolition if they were in a dangerous condition.  The markings carved on the pole nearest the site are consistent with markings used by the General Post Office (GPO – later the Post Office and now British Telecom) to indicate the size of the pole and its year of production.3 The carving on this pole indicates the year 1957.  The other pole has no carving on the side facing upwards, and it has not been possible to move it.

The east aerial mast bears a carved marking which is not very deep and is not easily seen, but it is sufficiently clear for the marks to be readable.  The marks consist of the letters GPO with a number 1908 immediately below, and the letter R below the number.  This format differs from that used on the telegraph pole, but it does suggest a GPO installation.  It occurs to me that the number may be the year of production, and that the lower section of this mast may be a heavy  telegraph pole recycled from an era when repeater amplifiers were not yet in use and poles carried numerous circuits on heavy copper wires.  If the lower section of west mast had also been recycled, then its markings could be at the top end.  Another observer has noted that the upper sections of the masts each bear a date carving indicating the year 1957.   Punch-hole inspection record plates are fixed to the masts.  This type of inspection record appears to have been in use from 1964.3


The nearest buildings to the aerial site are a cottage, and a brick shed with asbestos roof, standing close together about 150 metres from the aerial site.  The buildings do not resemble any typical building seen at telecommunication sites.  The occupier of the cottage states that the cottage is some 90 years old, and that the shed is used for shearing sheep.  There is no evidence of any building nearer the aerial masts.


There is no sign of a mains power supply to the site.  In this rural location it is likely that any mains power would be supplied by overhead line, but there is no trace of any power distribution poles.  Nor is there a trace of anything suggesting a supply from an underground power cable. A redundant power pole opposite the cottage does have two disused power line insulators, but these look likely to have supported overhead power lines to the cottage as the cottage has a rusty metal pole with two similar unused power insulators.  The two fallen telegraph poles do not have any power line insulators attached, those poles being fitted with only the spindles for telephone line insulators, a few of the insulators remaining intact.  Might the 50-Volt DC supply from the telephone system have been used for some low-power equipment on the site?

Some years ago an employee working in the Pentland Hills Ranger Service office at Boghall advised me that she had been told only that the masts dated “from the War”.  A later item in the Ranger Service newsletter said that research had revealed the masts were part of a high frequency aerial for receiving radio signals from South Africa in World War II, although the source of that information was not stated.Recent communication from the author of the newsletter item suggests that the information came from a former BT employee who was involved in the maintenance of the masts and former telephone lines to the old Boghall Farm office, and that the South Africa connection was also known anecdotally by the farm staff and by the estates team of Edinburgh University. (The University conducted agricultural research at the farm).

The features of the Boghall masts do not seem consistent with a typical commercial or government aerial installation for long-distance high-frequency (HF, otherwise referred to as short-wave) communication.  These sites occupy large areas, with substantial buildings, large high-gain aerials, and back-up power requiring fuel storage and generators.  Long-distance HF communication would have been adequately catered for by other sites established in the UK before the War.5, 6  To provide long-distance HF communication in the event of invasion in World War II, an emergency long-distance HF transmitting site was established at Saughton Mains in Edinburgh, associated with a new HF receiving facility at an existing GPO low-frequency (long wave) receiving site at Kemback near Cupar. 7, 8  The use of a distant site for receiving avoids the risk of breakthrough from the high power transmitter typically used for long-distance commuinication.  The existence of a transmitter site in Edinburgh with receiving facility at Cupar would rule out the use of Boghall as a receiving site for the long-distance system. 

The copper wires are not insulated from the masts, and therefore would not be suitable as a driven aerial element.  They could have acted as a reflector for some driven element in front.  The steelwork in front of the masts could conceivably have supported a short mast with some element capable of covering the HF spectrum, although gain would be limited unless a vertical stack of elements was utilised, which would then require some additional support.  Also, the site on a hillside seems more appropriate for higher frequencies, at VHF and above, where reliable wave propagation in normal conditions is limited almost to direct line of sight. The orientation of the masts would suggest a system with maximum sensitivity to signals from a bearing exactly due south from the site.  South Africa lies on a bearing of about 15 degrees to the east, not a crucial difference but one which might be significant given that this is clearly a professional installation.


The GPO did make use of low VHF frequencies for telecommunication links using rhombic aerials or curtain arrays of dipoles.  In the 1930s telephone circuits to offshore islands were provided by this method.9  In 1946 an experimental link was established using rhombic aerials at relay stations, between London and Castleton in Monmouthshire, and that link was used later to feed television signals to a local transmitter.10

During World War II the GPO established an emergency radio scheme to maintain inland telegraph communication in the event of disruption to land lines. This scheme used medium- and high-frequencies to link fixed stations at major towns and cities with existing coastal maritime radio stations.  The Edinburgh station was located at Dr Guthrie's Boys' School at Liberton.8   In addition, it appears that small receiving sites were installed near the main long-distance HF transmitting stations to permit remote operation by radio link (presumably at VHF)  from a central point in London if line communication was lost.7  It is not clear just how far these receiving sites were from the associated HF transmitter sites.  It seems that this provision applied only to the HF stations at Rugby and Leafield.8  

The masts appear on an Ordnance Survey map that has been dated 1947 (that date is now suspect as the map shows the modern artificial ski-slope at Hillend a short distance to the north).  A small rectangular structure also appears on that map, in alignment with the surviving steelwork.  11  In the absence of any sign of another possible need for the telegraph poles, it seems that they did serve the aerial site.  However, it does seem unlikely that a telegraph pole installed during World War II would need replacement as early as 1957, but that does remain a possibility.  If the telegraph lines were associated with the aerial site, then it can be assumed that the site was still in use in 1957.  However, the Saughton Mains area is shown on a map dated 1955 already covered with houses (the date of that map must also be treated with caution as it is taken from the same web source as the 1947 map).11 Continued use of the Boghall site in 1957 would exclude the possibility of a connection with the wartime emergency radio scheme, and possibly the long-distance facility at Saughton Mains.  Is it possible that the installation was repaired or amended in 1957, or was that the year of construction? 

Microwave technology was well-established by 1952, when the Manchester to Kirk o' Shotts link was operational.10  It seems improbable that in 1957 an older type of VHF system with limited capacity would be in use when microwave systems were already available for fixed short-distance links.   

All the evidence suggests that the installation was not part of a long-distance HF communication system, and thus that the story about communication with South Africa is wrong.  If this information did originate with an employee of the Post Office/BT, then did they or someone else within their organisation provide disinformation to conceal the true purpose of the installation?

About two miles east of the site, on the path from Bonaly to Glencorse, an old warning sign indicates that an area further west into the hills from Boghall was used for mortar and anti-aircraft practice.12 Exactly when that area ceased to be used is not known. The aerial system does not look like something intended for a simple communications facility on an exercise area.


Radar, navigational aids, electronic countermeasures, and signals interception facilities used during World War II have been fairly well documented, but I have been unable to find any information that might explain the structure at Boghall.  It has been pointed out that the GPO, as a department of government, was involved in close cooperation with the armed services.

It may be suggested that the Boghall installation simply provided mechanical support for some other device.  That seems unlikely since the wires on the masts are copper, which is more expensive and weaker than steel.  The choice of a good conductor like copper suggests at least some electrical purpose, although not necessarily related to radio.


Historic Environment Scotland have included several radio sites on their Canmore website, some of them of comparatively recent construction, but the Boghall masts seem to have escaped attention.13

I would be interested in any information or suggestions about this very peculiar installation, any recollections of the missing structure in front of the masts, or any details about similar aerials found elsewhere. 


2. Ordnance Survey map on smaller scale showing exact position of each mast is available on Midlothian Council planning portal at https://planning-applications.midlothian.gov.uk/OnlinePlanning/spatialDisplay.do?action=display&searchType=Application

3. Comparison with information on website of the Telegraph Pole Appreciation Society http://www.telegraphpoleappreciationsociety.org/36-telegraph-poles/hardware/55-telegraph-pole-hieroglyphics

5. Descriptions of typical long-distance HF receiving and transmitting sites  http://www.alancordwell.co.uk/Legacy/hfradio/BTRSint.html

7. A H Mumford:   Long-Distance Point to Point Communication (1947) Sections 2.1, 2.2, 2.3

8. BT Digital Archives

10.  https://www.theitp.org/knowledge_hub/historic/Short_History

11.  Digitised from Ordnance Survey archive.  Map dated 1947 at 1:2500 scale available at  https://www.old-maps.co.uk/#/Map/327500/673500/12/100954
 On the same website the masts are not shown on the 1:10560 scale dated 1955, but appear again on the 1:10000 scale dated 1976.