When the Football League resumed in 1946, Merrick found himself playing regularly for the recently renamed Birmingham City. In 1948, Merrick helped the club win the Second Division Two, missing only six games along the way. He played regularly for the Blues until the end of the 1954–55 season, when another Blues prodigy, Johnny Schofield replaced him in goal because of injury. During this time, Merrick achieved 126 league games in a row, from 15 April 1949 to 5 April 1952. He also played in every FA Cup game during this time, another nine games, including an FA Cup semi-final appearance against Blackpool, which the Blues lost 2–1.