2010–2024: The Vale of Glamorgan County Borough electoral divisions of Baruc, Buttrills, Cadoc, Castleland, Court, Cowbridge, Dinas Powys, Dyfan, Gibbonsdown, Illtyd, Llandow and Ewenny, Llantwit Major, Peterston-super-Ely, Rhoose, St Athan, St Bride's Major, and Wenvoe. Sully ward was transferred to Cardiff South and Penarth in 2010.
2024–present: Following the 2023 boundary review, the Vale of Glamorgan County Borough electoral divisions of Baruc, Buttrills, Cadoc, Castleland, Court, Cowbridge, Dyfan, Gibbonsdown, Illtyd, Llandow and Ewenny, Llantwit Major, Peterston-super-Ely, Rhoose, St Athan, St Bride's Major, and Wenvoe. The constituency lost 8.3% of its size after Dinas Powys was transferred to Cardiff South and Penarth.[4]
This marginal constituency to the west of Cardiff takes in the Labour-voting seaside resort of Barry and a number of Conservative villages and small towns, such as Cowbridge. There have been some close shaves for both parties here in the past: Conservative Walter Sweeney got home by a mere 19 votes in 1992; and John Smith had a majority of under 2,000 in 2005. John Smith stood down from Parliament due to ill health, and the seat went Conservative at the 2010 election.