Starting in Belfast, where his Professor was Heinrich H. Wagner (1923-1988), he studied Ulster Irish and Scottish Gaelic in his theses for the MA (1962) and PhD (1966) degrees, and between 1961 and 1965 he collected Scottish material for vol. IV (1969) of Wagner's Linguistic Atlas. In Aberdeen his interest soon turned to Gaelic verse of the period 1600-1730 and several volumes have been published (1972, 1979, 1994, 1995 and 1997), including an anthology with English translations by Meg Bateman (1994).
In the late 70s Breandán Ó Doibhlin, Professor of French at St Patrick's College, Maynooth, Co. Kildare, who visited the Highlands and became a student of the work of Somhairle MacGill-Eain, suggested that a collection of Scottish Gaelic short stories translated into Irish would be of interest in Ireland; this collection, Feoil an Gheimhridh, was published in 1980, reprinted 1996.
About 1980 and after, he co-operated with Cathair Ó Dochartaigh, then in the Department and now Professor in Glasgow, towards a major projected anthology of all the extant examples of the 17th-19th-century Irish verse form known as Trí Rainn agus Amhrán: 103 of them were found (one of them in Scottish Gaelic), some during sabbatical terms spent visiting collections of manuscripts both in Britain and in Ireland. Having finally overcome difficulties with four different publishers, they had a collection of the texts published in Belfast in 1996 - but without any of the academic apparatus. It is now hoped to publish the complete work within the next year or so.
As an offshoot of interest in Gaelic verse, a series of studies related to Gaelic manuscripts had begun as early as 1976, and around that time he was interviewed by Grampian Police investigating the theft of many of the MacNicol and other Gaelic manuscripts from the National Library. He succeeded in convincing them that his hands were clean, but the manuscripts have not been recovered. Probably his proudest academic moment to date was when he discovered (on 8th May 1985) the identity of the scribe of the first section of the National Library's Gaelic manuscript 72.1.1, dated 1467.
Interest in linguistic questions was rekindled in 1987 when he was invited to give the Ned Maddrell Memorial Lecture in Douglas, and shortly after that he translated the Irish version of a Welsh original to provide the Scottish Gaelic cartoon language course Gaelic is Fun! (1989, reprint 1991); a sequel, Gaelic is Fun-tastic!, is now with the publishers in Stornoway. Articles on various linguistic topics became more numerous in the 1990s, with some new emphasis on relations between Gaelic and Scots. Since meeting with Roderick D. Cannon and other piping scholars at the Edinburgh Celtic Congress in 1995, he has developed a research interest in the Gaelic terminology and nomenclature of piping. Work is continuing on the cataloguing of manuscripts of Gaelic verse, and (in collaboration with Dr John MacInnes, Edinburgh) on an edition of the songs of Mairghread nighean Lachlainn (?c.1670-post1750) for the Scottish Gaelic Texts Society.