People educated at Allan Glen's School

Sir Harold Montague "Monty" Finniston FRS FRSE (15 August 1912 – 2 February 1991) was a Scottish industrialist.

Sir Kenneth Charles Calman, HonFAcadMEd (born 25 December 1941) is a Scottish doctor and academic who formerly worked as a surgeon, oncologist and cancer researcher and held the position of Chief Medical Officer of Scotland, and then England. He was Warden and Vice-Chancellor of Durham University from 1998 to 2006 before becoming Chancellor of the University of Glasgow. He held the position of Chair of the National Cancer Research Institute from 2008 until 2011. From 2008 to 2009, he was convener of the Calman Commission on Scottish devolution.

Harry Duncan McGowan, 1st Baron McGowan KBE (3 June 1874 – 13 July 1961) LLD DCL, was a prominent Scottish industrialist who served as Chairman of Imperial Chemical Industries for 20 years.

Sir Robert Arthur McCrindle (19 September 1929 – 8 October 1998) was a Scottish Conservative politician. He was Member of Parliament for Billericay from 1970 to 1974 and Brentwood and Ongar from 1974 to 1992 (following boundary changes).