[3] He left school aged 15 in 1955 to work in the signal box in Gatehead walking 4.5 miles each way in all weather to get there.

When Sid Weighell resigned in 1983, Knapp was the successful left-wing candidate to replace him as General Secretary of the NUR.

Knapp had been a relatively junior union officer, having failed an exam to become assistant general secretary.

A "candidate from nowhere",[4] he beat the sitting assistant general secretary Charlie Turnock by a wide margin, despite Weighell describing him as "a stooge of the Communist and Trotskyite Left"[5] and "wet behind the ears".

He improved the NUR's relations with other rail unions, including ASLEF, and fought against closure proposed in the Serpell report on railway finances.

[5] He defeated a challenge for the union leadership in 1999 from Greg Tucker, winning a fourth five-year term as General Secretary.

After Knapp's death in August 2001, Bob Crow was elected as the new General Secretary of the RMT in February 2002.