John Antrobus married the former Margaret McCormick.

His father was a Regimental Sergeant-Major in the Royal Horse Artillery, and the family was stationed at the School of Artillery in Larkhill, on the edge of Salisbury Plain. Antrobus attended the Royal Military Academy Sandhurst to finish his education, but rebelled and dropped out of the Army.

After leaving the Army, John Antrobus pursued a future writing comedy, and went to Associated London Scripts (ALS), the writers cooperative set up by Spike Milligan, Ray Galton, Alan Simpson and others. Antrobus states "I met Spike in 1954 or 55. I had sent a sample script to Galton and Simpson and they took me on at Associated London Scripts". Antrobus and Milligan "wrote a couple of Goon Shows together. I wish I had done more of them with him but I wanted to be a playwright. I didn't realise they were golden times and how they gave life". The two shows were The Spon Plague, and The Great Statue Debate, both broadcast in March 1958

At ALS, Antrobus also worked with Johnny Speight on The Frankie Howerd Show in 1956, After contributing material to the first Carry On movie, Carry on Sergeant (1958), he wrote his first movie screenplay: for Idle on Parade (1959), starring Anthony Newley. During 1960 he worked with Milligan and Eric Sykes in the second series of Sykes and A... (August- September 1960). He was also a contributing writer to the television series The Army Game, in the 1958 and 1961 shows, along with Larry Stephens, Maurice Wiltshire, and Lew Schwarz in 1958, and Brad Ashton, Barry Took, Marty Feldman and Wilshire in 1961. During the 1960s and 1970s, he provided scripts for television series as diverse as That Was the Week That Was, Television Playhouse and Spike Milligan's Milligan in... Antrobus wrote for Milligan's last radio series, The Milligan Papers, a BBC Radio Collection released in 2002.

Antrobus' plays include The Bed-Sitting Room (1963) (co-written with Milligan) and a sequel from 1983; Cane of Honour (1965), Captain Oates' Left Sock (1969), An Apple A Day (1970) and City Delights (1978). In October 2005 Antrobus and Ray Galton (with whom he had collaborated on the 1986 sitcom Room at the Bottom and Get Well Soon from 1997) unveiled their play Steptoe and Son - Murder at Oil Drum Lane at the Theatre Royal, York. The Bed-Sitting Room was made into a film in 1969.

• First produced Edinburgh, 1964.
• First produced Royal Court Theatre, London, 1968. Televised 1971.
• First produced, Almost Free, London, 1968

• First published in Great Britain by Margaret & Jack Hobbs, 1970. Published by Universal-Tandem Publishing Co Ltd, 1972. © 1970 Spike Milligan and John Antrobus.

• First produced Royal Court Theatre, 1969
• First produced Gate Theatre, Notting Hill, London, 1980
• First produced Gate Theatre, Notting Hill, London, 1980
• First produced Gate Theatre, Notting Hill, London, 1980
• First produced, Mold, Clwyd, 1986.