Jack joined Chester FC in February 2025 from Kidderminster Harriers on a deal until the end of the season. From Newcastle, Jack’s first spell at Darlington between 2021 and 2023 was hugely productive, scoring 26 times in 88 appearances. In the 2022/23 National League North season, Lambert scored 16 goals including hat-tricks against AFC Telford and Gloucester City, before moving up to the National League with Kidderminster on a two-year contract in the summer of 2023. Jack made over 30 appearances last season in the fifth tier, contributing four goals and five assists. This season, he returned to Darlington on loan between November and the beginning of February, playing nine times.