His father, Ronald Dennis, was the son of a South Yorkshire coal hewer and served as a platoon commander on the Western Front in World War I.
[3][4] Dennis was evacuated during the war, residing with his paternal grandparents in the mining village of Wales, near Kiveton.
After the war, he was educated at Rutlish School, Merton (a state grammar school, where his father taught biology and physics), and St Catharine's College, Cambridge (BA 1954, MA 1959),[5] before studying for ordination at Cuddesdon College, Oxford.
"[7] Between school and university he spent a year of National Service serving with the Royal Air Force.
Following curacies in Armley and Kettering,[8] he was appointed vicar of the Isle of Dogs in 1962, transferring to John Keble Church, Mill Hill, in 1971.
[12][13] In 1956, Dennis married Dorothy Mary,[6] daughter of Godfrey Parker Hinnels (who fought at the first Battle of Arras in World War I).