Regarded until the Assembly election as a safe Labour seat, this has been held since 1995 by Don Touhig, who won it at a by-election called when the former Labour leader, Neil Kinnock, was appointed a European Commissioner. Mr Touhig increased his majority to 23,931 (or 65.7%) at the 1997 general election, leaving the Liberal Democrats in second place, the Conservatives third, and Plaid Cymru fourth.
Astonishingly the seat fell to Plaid Cymru in the Assembly elections with a swing in excess of 35%. Plaidís Brian Hancock beat the Labour candidate by six hundred votes. The seat forms part of the Caerphilly local authority area, which voted Yes in the 1997 devolution referendum by a majority of 5,989. Plaid Cymru hold the majority of council seats in Islwyn and overall control of the wider county borough.
Islwyn is a former mining district in south east Wales. The seat comprises the town of Risca on the Northern fringes of Newport, the relatively prosperous commuter town of Blackwood and the more deprived community of Newbridge. Islwyn is overwhelmingly English-speaking although it takes its name from an eponymous Welsh Language poet of the 19th Century.