Parliamentary Constituencies Act 1986
1. Parliamentary constituencies
(1) There shall for the purpose of parliamentary elections be the county and borough constituencies (or in Scotland the county and burgh constituencies), each returning a single member, which are described in Orders in Council made under this Act.
2. The Boundary Commissions
(1) For the purpose of the continuous review of the distribution of seats at parliamentary elections, there shall continue to be four permanent Boundary Commissions, namely a Boundary Commission for England, a Boundary Commission for Scotland, a Boundary Commission for Wales and a Boundary Commission for Northern Ireland.
SCHEDULE 2 Rules for Redistribution of Seats
1 (1) The number of constituencies in Great Britain shall not be substantially greater or less than 613.
(2) . . .
(3) The number of constituencies in Wales shall not be less than 35.
(4) The number of constituencies in Northern Ireland shall not be greater than 18 or less than 16, and shall be 17 unless it appears to the Boundary Commission [the Electoral Commission or (as the case may be) the Boundary Committee] for Northern Ireland that Northern Ireland should for the time being be divided into 16 or (as the case may be) into 18 constituencies.
2 Every constituency shall return a single member.
3 There shall continue to be a constituency which shall include the whole of the City of London and the name of which shall refer to the City of London.
[3A A constituency which includes the Orkney Islands or the Shetland Islands shall not include the whole or any part of a local government area other than the Orkney Islands and the Shetland Islands.]
4 (1) So far as is practicable having regard to rules 1 to [3A]-
(a) in England and Wales,-
(i) no county or any part of a county shall be included in a constituency which includes the whole or part of any other county or the whole part of a London borough,
(ii) no London borough or any part of a London borough shall be included in a constituency which includes the whole or part of any other London borough,
(b) in Scotland, regard shall be had to the boundaries of local authority areas,
(c) in Northern Ireland, no ward shall be included partly in one constituency and partly in another.....
5. The electorate of any constituency shall be as near the electoral quota as is practicable having regard to rules 1 to 4; and a Boundary Commission [the Electoral Commission or (as the case may be) a Boundary Committee] may depart from the strict application of rule 4 if it appears to them that a departure is desirable to avoid an excessive disparity between the electorate of any constituency and the electoral quota, or between the electorate of any constituency and that of neighbouring constituencies in the part of the United Kingdom with which they are concerned.
6 A Boundary Commission [The Electoral Commission or (as the case may be) a Boundary Committee] may depart from the strict application of rules 4 and 5 if special geographical considerations, including in particular the size, shape and accessibility of a constituency, appear to them to render a departure desirable.
General and supplementary
7 It shall not be the duty of a Boundary Commission [the Electoral Commission or (as the case may be) a Boundary Committee] to aim at giving full effect in all circumstances to the above rules [(except rule 3A)], but they shall take account, so far as they reasonably can-
(a) of the inconveniences attendant on alterations of constituencies other than alterations made for the purposes of rule 4, and
(b) of any local ties which would be broken by such alterations.
8 In the application of rule 5 to each part of the United Kingdom for which there is a Boundary Commission-
(a) the expression "electoral quota" means a number obtained by dividing the electorate for that part of the United Kingdom by the number of constituencies in it existing on the enumeration date,
(b) the expression "electorate" means-
(i) in relation to a constituency, the number of persons whose names appear on the register of parliamentary electors in force on the enumeration date under the Representation of the People Acts for the constituency,
(ii) in relation to the part of the United Kingdom, the aggregate electorate as defined in sub-paragraph (i) above of all the constituencies in that part,