West Yorkshire — Leeds, Bradford, Wakefield, Huddersfield — is one of the most densely populated parts of northern England, and that population supports a genuinely strong Pony Club, riding school and competition scene, with plenty of demand keeping the market active. The Pennine fringe to the west gives some hillier, hardier grazing, while the Aire and Calder valleys offer more typical lowland pasture.
Urban fringe pressure on grazing land is real here — good fields near the cities are sought after and command a premium, which feeds through into livery and, to some extent, pony prices. The upside of a dense population is choice: more adverts, more shows to see a pony compete at, and more chance of finding someone locally who knows a pony's history. Expect to compete with other buyers for the better ponies, and be ready to move quickly.