The Cuillin: UK's Toughest Mountain Survey?

© G and J Surveys

Earlier this week came news that Knight's Peak of Sgurr nan Gillean had been officially demoted from 'Munro Top' status, following the most accurate ever survey of its height by G and J Surveys, the team behind other recent Munro upsets and the addition of new mountains to England and Wales. In conjunction with The Scottish Mountaineering Club and The Munro Society, the team headed to Skye in September 2013 to painstakingly measure the height of Knight's Peak and the nearby Basteir Tooth. Unlike the straightforward walking terrain of their previous target summits, both peaks demand mountaineering skills. This could be the UK's most challenging mountain survey. Here's how they did it:

The Cuillin of Skye are renowned as having the most challenging mountain environment anywhere in Britain. These mountains contain narrow, complicated ridges where a day’s outing can require a mountaineer’s skill and knowledge to overcome their difficulties.

Having surveyed over 150 summits in the uplands of Britain, surveying was not new to us, but none compared to the task we now set ourselves as the Cuillin are like nothing else in Britain.

The two summits we aimed to survey were Knight's Peak (NG471254) and the Basteir Tooth (NG465252) both being classified as Munro Tops in the latest edition of Munro’s Tables, the 3,000ft Scottish mountains first listed by Sir Hugh Munro and published in the 1891 Scottish Mountaineering Club (SMC) Journal. The list consists of Separate Mountains, eponymously known as Munros, and Subsidiary Tops, now known as Munro Tops. They form part of the most popular list of mountains in Britain.

"With over 150 summits done, surveying was not new to us, but none compared to the task now. The Cuillin are like nothing else in Britain"

Alan Dawson and Leica1250 on Knight's Peak  © G and J Surveys
Alan Dawson and Leica1250 on Knight's Peak
© G and J Surveys
The survey team on the Basteir Tooth  © G and J Surveys
The survey team on the Basteir Tooth
© G and J Surveys

As Knight’s Peak had a map height of 915m (3,002ft) and the Basteir Tooth 916m (3,005ft) each summit was close to the qualifying height of 3,000ft. As these map heights have a margin of uncertainty of +/-3m we wanted to obtain an accurate and definitive height for each using the latest GPS technology.

Knight’s Peak is generally climbed as one of several summits on the classic Pinnacle Ridge route up to Sgurr nan Gillean; this is the standard way to its summit and requires climbing up to Moderate/Difficult grade, and abseiling skills. Whichever way one approaches Knight’s Peak, the minimum requirement to reach its summit is a scramble.



The summit area of Knight’s Peak consists of two tops a short distance apart. One top is spacious enough for one person to balance on top, whilst the other is a pointed top where standing is not advised. The land beyond the summit area is precipitous. 

The Knight’s Peak survey was conducted in conjunction with the SMC and The Munro Society (TMS), whilst the survey of the Bastier Tooth was organised by The Munro Society. The participants for this most difficult of mountain surveys gathered at Portnalong on the Isle of Skye in early September 2013.

The 11th of September dawned wet and dank but with a limited time frame on Skye and a forecast of improvement we took our opportunity and set out for Knight’s Peak.

What gear do they use?

Leica NA730 Professional Automatic level (X30 telescopic system)/tripod system and a "1m" E-staff extendable to 5m. This equipment lets you determine exact summit position.

Leica Geosystems Viva GS15 Professional receiver. This instrument determines its position and height from the constellations of GPS and GLONASS satellites. By linking data from the GS15 to those produced by the network of Ordnance Survey base stations, position can be determined to within 1cm and height to within 5cm, given sufficient data collection times. Using this you can determine the absolute height of your chosen spot.

Following the path that starts near the Sligachan Hotel, we made good progress beside the clear waters of the Allt Dearg Beag. We walked up into the mist reaching the high Coire Riabhach and headed for a chimney gully between Sgurr nan Gillean and Knight’s Peak, where the party donned helmets and harnesses as this part of the route has a Difficult rock climbing grade.

Beyond the gully an airy rising traverse led to a small ledge on the crest of Pinnacle Ridge, followed by a higher traverse giving access to the two summits of Knight’s Peak. Our preliminary assessment with the Abney level made the northerly summit about 0.1m higher. Soon our GS15 was set up on a small tripod and aligned with the high point of this summit, whilst Alan Dawson placed his Leica RX 1250 on the highest point of the southerly summit. A two hour vigil now started as Ordnance Survey requires a minimum two hour data set for verification of the result.

Nearing the end of the survey the mist began to lower and blue sky appeared above, while below us pinnacles of rock thrust their way up through the mist as the breathtaking spectacle of a Brocken Spectre appeared. All that remained was to pack the equipment away and carefully head down our inward route.


Basteir Tooth, Am Basteir, Cuillin, Skye  © wee jamie
Basteir Tooth, Am Basteir, Cuillin, Skye
© wee jamie, Nov 2010

Two days later we set out for the Basteir Tooth and although showers were forecast, the outlook for the day was good. Making our way up beside the Allt Dearg Beag we followed the path up to the base of Pinnacle Ridge. The morning’s sunshine was soon replaced with lowering cloud and the day’s first shower, as we followed a scree path toward the Bealach a’ Bhasteir. The way to the Basteir Tooth was over the Munro of Am Basteir. Negotiating its ‘Bad Step’ with the aid of a rope, we reached the summit of Am Basteir and just beyond we abseiled down a short overhanging pitch to reach the narrow confines of the bealach between Am Basteir and its Tooth.

The survey equipment was soon in place and aligned for its two hour of data collection. Once the data set had been gathered and the equipment packed away we slithered down the Tooth and squeezed down through a hole and small cave to a chamber with an abseil point. From here we abseiled down the 80ft of vertical rock which is the sidewall of King’s Cave Chimney to a steep scree slope below and the path back to the awaiting cars.

The data sets were sent to Mark Greaves at Ordnance Survey, who kindly processed them. But what of the result, would the Basteir Tooth and Knight’s Peak remain Munro Tops? The result confirmed by Ordnance Survey is that the Tooth is 917.16m (3,009ft) and Knight’s Peak is 914.24m (2,999ft 5½″). The SMC, who are custodians of the Munros and Tops list have adopted this height for Knight’s Peak. Therefore it just fails to retain its Munro Top status by an approximate 6½ inches.

But it doesn't take anything away from the hill. The hill is still there and it is a fantastic hill. It is just the categorisation that has changed.



G and J Surveys was formed by Graham Jackson and John Barnard in June 2006.  Myrddyn Phillips joined the team in May 2007. They carried out the surveys that have reclassified Sgurr nan Ceannaichean and Beinn a'Chlaidheimh from Munro to Corbett status, as well as finally determining that Buidhe Bheinn is the higher summit of the infamous twin Corbett. South of the Scottish border their surveys have elevated Mynydd Graig Goch and Thack Moor to 2000ft mountain status. Where next for the team..?


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