John McNab was more commonly known as 'Jock' because of his Scottish ancestry. He was a wing-half who was on Liverpool's books for several seasons from the end of the First World War. He arrived on Merseyside in November 1919 and made his debut for the club at home to Manchester United on New Year's Day, 1920. He also played in the next First Division fixture at Sheffield United two days later but those were his only 'starts' in 1919-20 and he was only selected once in the following season.
John Bamber started the 1921-22 season at right-half but only lasted four games before he was replaced by Francis Checkland for the next five. John came in for the 10th match against Preston North End and only missed four First Division games between then and the end of the season, picking up a League championship medal in the process, something he would also experience a year later, when he missed just three of the 42 matches.
He would continue to be a regular member of the club's defence for another four years until he moved south to join Queens Park Rangers at the end of the 1927-28 season. McNab played in exactly 200 league fixtures for Liverpool, with a further 21 appearances in the FA Cup and one in the Charity Shield.