Barclay was educated at Harrow School, before reading Classics at Trinity College, Cambridge, where his first foray into show business was via the Amateur Dramatic Society.
He then appeared in Cambridge Footlights revues alongside Tim Brooke-Taylor, Bill Oddie, John Cleese, Graham Chapman, David Hatch, Jonathan Lynn, Jo Kendall and Miriam Margolyes.
In 2000, Barclay was adopted into the royal family of Tafo, a village which is a three-hour drive north-west of Accra in the Kwahu region of Ghana, while there to attend the funeral of his friend, the actor Christopher (Gyearbuor) Asante.
He is a descendant of David Barclay of Youngsbury (1729–1809), a Quaker banker who famously manumitted all of the slaves he acquired in English Jamaica as the result of a debt.
[4] In 2016, through an introduction via Verene Shepherd, the Jamaican historian of diaspora studies, Humphrey Barclay met with a distinguished African American descendant of one of the slaves freed by his ancestor.