Crosby was a constituency in Merseyside, represented in the House of Commons of the Parliament of the United Kingdom from 1950 until 2010.

However, Williams lost the seat to the Conservative candidate Malcolm Thornton at the 1983 general election.

1983–1997: The Metropolitan Borough of Sefton wards of Blundellsands, Harington, Manor, Molyneux, Park, Ravenmeols, Sudell, and Victoria.

1997–2010: The Metropolitan Borough of Sefton wards of Blundellsands, Church, Harington, Manor, Ravenmeols, and Victoria.

Following a review by the Boundary Commission for England, the Crosby constituency was abolished at the 2010 general election.