Background
Threlfall was born in Morecambe, Lancashire.
Threlfall was born in Morecambe, Lancashire.
He played for Morecambe F.C. before joining Sunderland, but moved on to fellow First Division club Birmingham in July 1927 without having played for Sunderland"s first team Threlfall made his debut in a 1–0 defeat at Tottenham Hotspur on the opening day of the 1927-1928 season, and he and Arthur Johnson shared the outside left position for the next couple of months. In November 1927 Birmingham signed Billy Ellis, the winger who had kept him out of the Sunderland team, and both Threlfall and Johnson moved on at the end of the season without playing again.
After only three appearances for Bournemouth & Boscombe Athletic in the Third Division South, Threlfall returned home to non-league football with Morecambe and later with Lancaster Town.