John Finnemore was born in Reading to parents David and Patricia and has a younger sister, Anna.

[2] He then studied English at Peterhouse, Cambridge, where he wrote his dissertation on Thomas Hardy ('Icons, Frames and Freedom in Jude the Obscure') and graduated in 2000.

[6] Finnemore wrote the BBC Radio 4 sitcom Cabin Pressure and played the part of the "consistently cheery steward" Arthur.

[8][9] He also wrote a radio sketch show, John Finnemore's Souvenir Programme, which he performed with Simon Kane, Carrie Quinlan, Lawry Lewin and Margaret Cabourn-Smith.

A stage version of Souvenir Programme, renamed John Finnemore's Flying Visit, completed two UK tours.

In September 2011, Finnemore wrote a pilot episode for BBC One called George and Bernard Shaw, a sitcom starring Robert Lindsay and Richard Griffiths as an elderly gay couple.

In this period, he became the fourth person to win a prize for solving Cain's Jawbone, a literary puzzle created by Edward Powys Mathers in 1934.

[25] Finnemore was also a co-writer, with Neil Gaiman, of the second series of Good Omens, which starred Michael Sheen and David Tennant.

In 2014 Finnemore was the narrator for 24 Hours to Go Broke on Dave in the episodes "Iceland", "Greece", "Germany", "Ireland" and "Armenia".