This seat has had a chequered political history at Westminster. It was held through three decades by Cledwyn Hughes for Labour until the Conservatives unexpectedly captured it when the Tories came to power in 1979. The Tories retained it in 1983, although Plaid Cymru had by that time emerged as the main challenger.
Aided by the Tory MP Keith Best's disgrace over a share deception, Plaid's Ieuan Wyn Jones snatched the seat in 1987, retaining it with narrow majorities over the Conservatives in 1992 and Labour in 1997.
Anglesey is a predominantly rural island, although it has some heavier industry around Holyhead, where the ferry terminal is an important employer. Agriculture and tourism are major industries, and there is also a substantial retirement population.
The island is predominantly Welsh-speaking, with 62% of the population registering as Welsh speakers.
Anglesey Aluminium is the island's largest employer (550 people). The DTI's decision to lift the moratorium on gas-fired power stations means that a new one could be built on the island, safeguarding the aluminium jobs and creating around a hundred more.