[3] In his first season at the club he started in the 2019–20 Premiership Rugby Cup final which they lost against Sale Sharks to finish runners up.
[4] Northmore was a replacement in the Premiership final against Exeter Chiefs on 26 June 2021 as Harlequins won the game 40–38 in the highest scoring Premiership final ever to become league champions.
[5] In April 2024, Northmore scored twice against league leaders Northampton Saints in a 41-32 victory at Twickenham Stadium for the Big Summer Kick Off.
[6] The following month he started in their European Rugby Champions Cup semi-final elimination against Toulouse.
[7] Northmore was called up to the senior England squad for the 2022 Six Nations Championship.