Born in North Seaton in Ashington, Lynn studied architecture at Durham University, then worked for the East Anglia Health Board, followed by Coventry City Council. Gaining experience in the design of council housing, he became well known for designing the large Park Hill complex in Sheffield, with Ivor Smith. When Lewis Womersley, the Sheffield City Architect, moved to Manchester in 1964 to join in private practice with Hugh Wilson, Lynn moved to Manchester where he was principal architect in the office. He oversaw preparation of a plan for the Higher Education Precinct, for the Arndale shopping centre subsequently bombed by the IRA and for the development of Hulme, where Park Hill's principles of design proved less readily transferred to a flat site. In the late 1960s Lynn returned to the North East of England, working on the development of Newcastle University's campus and forming Kendrick and Lynn Associates, designing various Roman Catholic churches.
- Rakesh Ramchurn, "Park Hill architect Jack Lynn dies, aged 86", Architects' Journal, 24 October 2013
- "Pioneer behind Sheffield’s Park Hill complex dies aged 86", The Star, 22 October 2013