McLauchlan was educated at Ayr Academy and Jordanhill College and was the first member of his school and club to be capped by Scotland. McLauchlan won his first cap in 1969 and went on to play until he was 38. In 1971 he was selected to tour with the British Lions as understudy to Ray McLoughlin in Australia and New Zealand. He completed the tour having played in all four of the Tests but got his chance mainly due to an injury to Ray McLoughlin in a violent match against Canterbury.

Nicknamed ‘Mighty Mouse’ he was an intense tourist in all facets and gained huge respect from fellow tourists and opponents alike. In 1973 he was appointed captain of Scotland and went on to lead them a total of 19 times. Again a British Isles tourist in 1974, McLauchlan was an integral part in the Lions pack.