 He was Chairman of the Gaelic Books Council 1968–91; President Scottish Gaelic Texts Society; former member of Scottish Arts Council and was the first recipient of the Ossian Prize in 1974.Professor Thomson was Chairman of the SNP's Gaelic Committee in the Seventies.He is the author of numerous books including "An Introduction to Gaelic Poetry", "The Companion to Gaelic Poetry", "European Poetry in Gaelic", and collections of Gaelic poetry, including his collected poems "Creachadh na Clàrsaich" (Plundering of the Harp/clarsach) which shared the Scottish Book of the Year Award in 1983.