Gilbert McClatchie joined the Socialist Party of Great Britain in 1910 and was soon fully involved in a range of activities which was to include writing, speaking, conducting study classes and long years of service on the Editorial Committee and the Executive Committee. He was already writing articles for the Socialist Standard before the first world war. After the 1939-45 war he was Party candidate in a Parliamentary election.
His father was a farmer in Ireland. Getting into financial difficulties, the family came to England when he was six years of age. Returning to Ireland in 1915, to avoid being conscripted to kill fellow workers, Gilmac (as he was known) did a variety of jobs including a long spell at timber felling. He got to know many of those active in the Irish trade unions and Labour Party and the Republican movement, with all of whom he argued the SPGB case. Some of his articles (on occasion written jointly with Mick Cullen) dealt with the "Irish Problem". He wrote a valuable series of articles in 1921 on the Russian Revolution and why Bolsheviks' tactics could not lead to Socialism.
His association with the Party was an outstanding example of mutual benefit. He brought his wide knowledge of history, economics and the working-class movement to the service of Socialism, but, as he explained, it was the stimulus of his membership that led him to study Marx and many other economists, to read Greek and Roman history and to tackle Hegel and other philosophers and the works of anthropologists. His first acquaintance with Marx's Capital was seeing it in a bookshop and buying it under the impression that it would help him with his job as a book-keeper.
Between the wars he was happily able to combine his love of books with travelling round the country buying and selling rare works on history, economics, etc. His bookshop, which gave him welcome opportunities to meet writers and collectors, was put out of action by the second world war.
His great knowledge served the Socialist movement well in the formulation over the years of the SPGB's contribution to political and economic thought. He wrote a full-length book for the centenary of The Communist Manifesto in 1948, covering developments of organisation and theory in a century of working-class history. Unfortunately no publisher could be found. He wrote the introduction to the Party's edition of The Communist Manifesto and drafted its 1975 pamphlet on the Materialist Conception of History.