[2] 1997–2010: The Borough of Thamesdown wards of Central, Chiseldon, Dorcan, Eastcott, Freshbrook, Lawns, Park, Ridgeway, Toothill, Walcot, and Wroughton.

It covered the southern half of the town as well as farms, villages and hamlets to the immediate south and east of Swindon.

2010–2024: The Borough of Swindon wards of Central, Covingham and Dorcan (part), Eastcott, Liden + Eldene and Park South, Lydiard and Freshbrook, Old Town, Chiseldon and Lawn, Ridgeway, Shaw, Mannington and Western (part), Walcot and Park North, and Wroughton and Wichelstowe.

The boundary ran from Dorcan across to Bishopstone and then down to Russley Park before turning west to Barbury Castle.

These patterns suggest a seat that is more marginal than its neighbour Swindon North, and one which has acted as a bellwether of the national result.