Slater started his career as a 16-year-old amateur at Blackpool in 1944 and played in the 1951 FA Cup Final in which Blackpool lost to Newcastle United, becoming the last amateur to play in an FA Cup Final at Wembley. Another record he jointly holds is Blackpool's fastest-ever goal: 11 seconds into a game against Stoke City on 10 December 1949. This was matched by James Quinn in 1995. Slater made his Blackpool debut on 10 September 1949, in a goalless draw at Aston Villa. As an inside-forward, he competed with Allan Brown for the number 10 position for the majority of his time at the seaside.