Date of birth
The centre-back joined Danny Cowley's side ahead of the 2021/22 season and was appointed captain.
A former Scotland under-21 international, he began his career with Aberdeen before moving south of the border to sign for Blackpool in 2015.
Robertson made more than a century of appearances during his time at Bloomfield Road and netted in a victory at Fratton Park.
He was part of the side that won the League Two play-off final in May 2017, playing the full 90 minutes of the Wembley success over Exeter.
Robertson moved to Rotherham the following year and helped secure promotion to the Championship, scoring five goals in 69 games for the Millers.