Basildon was a parliamentary constituency represented in the House of Commons of the Parliament of the United Kingdom.

Basildon was one of the best known bellwether constituencies in Britain, having voted for the winning party in each election for the duration of its existence.

It was a (famously) Conservative seat between 1979 and 1997 as the quintessential "Essex man" constituency based on the new town of Basildon.

Much of its population has its origins in the East End of London, who as a group traditionally voted for the Labour Party.

The MP throughout that period was David Amess, who himself originated from east London (Plaistow), and later held the safer seat of Southend West.