6. c. 41) was an act of the Parliament of the United Kingdom that established permanent boundary commissions for each of the constituent countries of the United Kingdom, and provided for the periodic review of the number and boundaries of parliamentary constituencies.

[1] The rules continuing into the 21st century for the redistributions of seats in the House Commons evolved from the Speaker's Conference in 1944.

The conference recommended an electoral quota for Great Britain calculated from the electorate and a 25 per cent tolerance on either side and that the total number of Members of the House of Commons should remain substantially the same with the Northern Ireland seats fixed at 12; the number of Scottish seats should be not less than 71 and the number of Welsh seats not less than 35.

This was swiftly enacted in the House of Commons (Redistribution of Seats) Act 1944.

In the period 1944 to 1958, the primacy of equality rule was diluted in five ways by further legislation:[2] Thereafter, the rules were only subject to minor change by statute, mainly to take account of changes in local authority structures.