Versatile forward Sean Lonsdale begun his career at Rygbi Gogledd Cymru (RGC) in North Wales but was recruited by Exter Chiefs during the summer of 2016. Lonsdale was a part of the rise of the Chiefs in recent years featuring for the club in the Gallagher Premiership, European Champions Cup and Premiership Rugby Cup. The Manchester born forward featured 62 times, scoring five tries since his debut in an nglo-Welsh Cup game away to Worcester Warriors in January 2018.

As well as featuring for the Chiefs, Lonsdale has also enjoyed loan spells in the National Leagues with both Plymouth Albion and Taunton Titans. The forward ended his six-year stay in Devon to make the move back to Wales where he joined the Dragons on a long-term deal ahead of the 2022/2023 season. Lonsdale made his Dragons debut in the opening league fixture against Edinburgh in Scotland and became a regular in the matchday squad throughout his debut campaign, making 19 appearances across all competitions.