Belfast East was a predominantly Unionist area with some pockets of labour strength, returning four Unionists in 1921 and 2 Unionists, 1 Independent Unionist and a Northern Ireland Labour Party MP in 1925. After 1929 the safe unionist seat of Bloomfield elected only Unionist MPs but Dock had an Independent Unionist representative in 1953-58 and an Independent Unionist support O'Neill in 1969–73. Victoria elected a NILP MP for two terms (1958–65) but was otherwise represented by Unionists. The mostly non-unionist Pottinger was won by an NILP then Independent Labour MP 1929–49. Another NILP member served 1958–69.
Belfast North was a predominantly Unionist area with some pockets of labour strength, returning four Unionists in 1921 and 2 Unionists, 1 Independent Unionist and a Northern Ireland Labour Party MP in 1925. Clifton was only represented by Unionist MPs, apart from an Independent Umionist 1953-58 and Pro-O'Neill Unionist 1969–73. Duncairn only had Unionist MPs. Oldpark had Northern Ireland Labour Party members 1945-49 and 1958–73. Shankill had an Independent Unionist MP 1929–53.
Belfast South was a strongly Unionist area, returning four Unionists in 1921 and 3 Unionists and 1 Independent Unionist MP in 1925. Ballynafeigh, Cromac, and Windsor only elected Unionist MPs. Willowfield elected a NILP MP in a 1941 by-election. He was re-elected for the Commonwealth Labour Party in 1945 but by the time of the 1949 election he was a Unionist. A Pro-O'Neill Unionist served as MP 1969–73.
Belfast West was a predominantly Unionist area with some pockets of Nationalist strength, electing 3 Unionists and 1 Nationalist in 1921 and 2 Unionist, 1 Independent Unionist and 1 Nationalist in 1925. Central and Falls never elected a Unionist MP. Central had a Nationalist MP 1929–46, a NILP MP elected in 1946 who by 1949 was Independent Labour until 1965, then a NDP MP 1965-69 and a NILP one 1969–73. Falls elected a Nationalist 1929–42, a Republican 1942–45, a Socialist Republican from 1945 who by 1953 represented the Republican Labour Party until 1969-73 when the Northern Ireland Labour Party held the seat. St. Anne's was always Unionist. Woodvale was represented by an Independent Unionist 1929-50 and a Northern Ireland Labour Party legislator 1958–65.
1969-1973 U 10, NILP 2, O'N U 2, Rep LP 2 (12th Parliament) (see note h)
Notes:-
(a) Joseph Devlin (N) was also elected for Antrim but chose to represent Belfast West. An Ind U gained a seat from U in a Belfast South by-election in 1923.
(b) P.J. Woods (Ind U) was elected in Belfast South and Belfast West. He decided to represent Belfast West. A U candidate won the by-election to fill the vacancy.
(c) In 1934 the MP for Pottinger was expelled from NILP and became Ind Lab
(d) 1941 the NILP gained a seat from U at a by-election, but the MP formed the CWLP before the next election. In 1942 Rep gained a N seat.
(e) In 1946 the NILP won a N seat. The CWLP MP became U before the next election.
(f) A NILP MP became Independent Labour and a Soc Rep MP became Rep LP before the next election.