Ben Macdui

The most useful sceptics of the Big Grey Man have always been the people who know the mountain best, and most of them are on the record with names. Start with the optics, because they are documented on this summit and they predate Collie by sixty years. In 1831, according to Affleck Gray — who takes it from John Hill Burton's The Cairngorm Mountains and whose two mentions of it give the journal's title slightly differently, so we flag it as second-hand — Sir Thomas Dick Lauder published in the Edinburgh New Philosophical Journal an account of ascending Ben Macdui with Mr Grant of Ballindalloch and seeing the phenomenon called the Spectre of the Brocken — an observer's own shadow thrown by a low sun onto a wall of mist, magnified out of scale and distorted by every movement of the air and of the observer. When the shadow's head is ringed with coloured bows the effect is called a glory, and the physics is diffraction of light at the edge of water droplets, not refraction. It is not a marginal curiosity: standing on the summit of Ben Nevis in the late summer of 1894, the physicist C. T. R. Wilson was so struck by coronas and glories that he set out to reproduce them in the laboratory, and the apparatus he built on the way became the cloud chamber that won him the Nobel Prize in Physics in 1927. The footsteps have a plainer explanation and a named advocate. William Garden, president of the Cairngorm Club when Collie spoke, called the suggestion of a Big Grey Man "perfect nonsense", and in a letter to The Scotsman on 28 March 1941 he explained why in the first person: he had more than once been convinced, walking a moonlit Aberdeenshire road in winter, that he heard footsteps crunching in the snow behind him, had been almost afraid to look round, and on looking round found it was "pure imagination". The Club's own journal, reporting the storm of correspondence that followed the dinner, noted that some readers had written in about mysterious music heard on the Cairngorms "which proved to be due to the sound of the wind rising and falling in gullies". Snow underfoot, wind in granite gullies and a walker's own boots reaching him a fraction late off the boulder field will produce a delayed crunch without any help. The base rate matters too. Robert Clark, interviewed in December 1925 after nearly forty years in the Cairngorms, said he had been alone at the cairn of Ben Macdui in eight months of the year and had crossed the plateau more than a hundred times without a single untoward experience — nothing, he said, except the Spectre of the Brocken. Sir George Adam Smith, former Principal of Aberdeen University, had never in his life heard a whisper of a spectre on the mountain. Even the most spectacular witness ended up on this side. Alexander Tewnion, the man who shot at the Grey Man in 1943, spent the closing pages of The Scots Magazine in 1958, and a long article in the Cairngorm Club Journal in 1999, taking his own story apart. His conclusion was that the footfalls were most probably a rock dislodged by deer or a freak of wind among the screes, and the charging shape a wraith of cloud enlarged by mist and by an imagination that already knew the story. He had already learned the lesson in 1939, when a twenty-foot hooded giant above the pines at Luibeg turned out to be smoke from a campfire, and he learned it from the other side in the summer of 1972: crossing the plateau near the Feith Buidhe in mist, grey-trousered, grey-cagouled and above average height, he found himself being followed at a nervous distance by three walkers who had taken him for the Big Grey Man. He got them off the hill safely and told them: "Maybe you'll remember your Ferla Mor — a benevolent ghost, not a malevolent ogre." What about infrasound? The idea that very low-frequency sound produces unease and a sense of presence is real and is usually credited to Vic Tandy, who in 1998 and 2000 published in the Journal of the Society for Psychical Research on a standing wave of around 19 Hz in an enclosed workshop and in a cellar. Two things need saying. First, no infrasound measurement has ever been published for the Ben Macdui plateau, so transferring the mechanism from a sealed room to an open mountain top is a guess, not a finding — that is true as far as we can establish in August 2026, and it is why this entry no longer repeats the claim that the Grey Man is caused by wind-generated infrasound. Second, the hypothesis has been tested and criticised by name: Jason Braithwaite argued in 2006 that a specific effect of infrasound in anomalous experiences had yet to be empirically demonstrated, and in 2009 Christopher French and colleagues built a chamber and put 79 people through fifty minutes of infrasound, complex electromagnetic fields, both or neither. Plenty of participants reported anomalous sensations; the number reported had nothing to do with which condition they were in. Their conclusion, in Cortex, was that the most parsimonious explanation was suggestibility. Finally, the name. Am Fear Liath Mòr sounds like deep Gaelic tradition, and it may be, but the documentary trail is thinner than the phrase suggests. Affleck Gray, who wanted the tradition to be old and looked hardest for it, concluded that the evidence for a pre-Collie legend "is meagre, and barely sufficient to satisfy the critical mind": he could list a long run of Derry and Luibeg stalkers and Corrour bothy watchers from the mid-nineteenth century onwards who never mentioned the Grey Man, note that the Rothiemurchus laird knew nothing of it beyond what he read in the press, and observe that the district's own Gaelic poet, William Smith of Rynuie, left no mention of the Fear Liath Mòr in any of his songs. The earliest use of the Gaelic name in the case itself is reported speech at two removes: Collie in 1925 relaying what Colin Phillip had been told by an old man at the edge of Rothiemurchus Forest — "Oh, aye, that would have been the Ferla Mhor he would have been seeing." Alexander Tewnion, hardly a hostile witness, wrote in 1999 that before Collie spoke there was "little more than a few meagre hints in local legend and folklore" to support a spectre on Ben Macdui. We checked that against the one corpus that ought to know. The Cairngorm Club Journal has appeared since 1893 and its complete run was digitised and made text-searchable in 2019. Searching it in August 2026, the phrase "Fear Liath" returns 2 hits, the earliest from 1977; "Ferla Mhor" returns 8, the earliest being Robert Clarke's aside of 1922; "Grey Man" returns 16. The control searches in the same index rule out a broken search: "Lairig Ghru" returns 69 hits and "Bodach" returns 10, including John Milne's Gaelic place-name study of Kirkmichael in Banffshire, published by the Club in 1906, which duly records bodach as the local word for a ghost or spectre. The same journal that printed Collie in 1926 remarked in the very same article that the Cairngorms had two other legends "of this character" — the spectre with the bloody red hand in Glen More, and a ghost on Bynack shot with an arrow — without claiming the same standing for the Grey Man. The Gaelic name is documented from 1922 onwards. Older than that, it is oral, second-hand and unfixed.