The House of Commons (Redistribution of Seats) Act 1944 set up Boundaries Commissions to carry out periodic reviews of the distribution of parliamentary constituencies.

It also authorised an initial review to subdivide abnormally large constituencies in time for the 1945 election.

[3] This was implemented by the Redistribution of Seats Order 1945 under which South East Essex was divided into two constituencies.

The Rural District of Rochford, and the parts of the County Borough of Southend-on-Sea (Shoeburyness), included in the new constituency of Southend East.

Benfleet, Canvey Island and Rayleigh were transferred back from Billericay, and Rochford from Southend East.