Scion of a Somerset gentry family originally of Welsh extraction, the only son of Sir Cullum Welch (1895–1980) and Gertrude née Harrison (1896–1966), he was educated at Marlborough College, before going up to Hertford College, Oxford,[1] graduating BA proceeding MA.

[3] Commissioned into the Royal Signals for National Service (1952–54), Welch saw action at Suez (GSM with Canal Zone Clasp).

[6] His father having served as Lord Mayor of London for 1956/57,[7] Sir John pursued a life in public service.

He was elected a Common Councilman for Walbrook 1975–86[8] and served as Chairman of the City Corporation's Planning and Communications Committee (1981–82).

[12] Married to (Margaret) Kerry Douglass on 25 September 1962, Sir John and Lady Welch had issue: