1. ^Campbell Stephen was elected as an Independent Labour Party MP in the 1945 general election but moved to the Labour Party in 1947, 4 days before his death. The seat was won by Labour in the 1950 general election.
2. ^¹ Constituency abolished in 1950.
3. ^Down was a two member constituency. Little was elected as an official Ulster Unionist in the 1939 Down by-election. Prior to the 1945 general election he resigned from the party in protest at being subject to a reselection due to the retirement of Viscount Castlereagh, the other official Unionist MP, and held his seat as an Independent Ulster Unionist. Multi-member constituencies were abolished at the 1950 general election, but the Ulster Unionists won both successor seats, North Down and South Down.
4. ^The last uncontested by-election on the British mainland to date.
5. ^¹ Both Pym and Campbell died after the close of polling, but before the declaration. They were returned at the head of the poll in their respective constituencies, and declared elected posthumously.
6. ^Dobbs was killed in a road accident the day after his election, making him the shortest-serving MP in British history.
7. ^^1 2 3 4 Gain not retained at the 1945 general election.
8. ^^{1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68} An uncontested election.
9. ^Seaborne Davies retained Caernarvon Boroughs for the Liberals in the by-election but lost the seat to the Conservatives in the 1945 general election.
10. ^In the 1945 general election Millington was the only successful Common Wealth candidate. He joined the Labour Party in April 1946.
11. ^^1 2 The Combined Scottish Universities was a three-member constituency which experienced three by-elections in this Parliament, each won by a different party from both the others and the general election. In the 1935 general election it elected two Conservative and one National Liberal MPs. One Conservative (Noel Skelton) died between polling and the declaration of the results and the resulting by-election was won by Ramsay MacDonald for National Labour. He died within two years and the resultant by-election was won by Sir John Anderson as a non-party supporter of the National Government. In 1945 the National Liberal member (George Morrison) resigned and the resulting by-election was won by John Boyd-Orr as an Independent. Both Anderson and Boyd-Orr held their seats at the 1945 general election along with one Conservative.
12. ^Prior to the by-election White was the Labour prospective parliamentary candidate for the constituency but resigned in order to contest the seat in defiance of the truce between the parties. In Parliament he took the Labour whip and retained the seat in the 1945 general election as an official Labour candidate.
13. ^Loverseed gained Eddisbury for Common Wealth from the Conservatives in 1943, but subsequently sat as an independent Labour member then took the Labour Party whip. He defended the seat in the 1945 general election for Labour but lost to the National Liberals.
14. ^Beattie won Belfast West for the Northern Ireland Labour Party but subsequently sat as an independent Labour member, under which label he held the seat in the 1945 general election.
15. ^In Parliament Driberg took the Labour whip and retained the seat in the 1945 general election as an official Labour candidate.
16. ^^{1 2 3 4 5 6 7 8 9 10 11 12 13 14} Gain retained at the 1945 UK general election.
17. ^Grigg was the newly appointed Secretary of State for War and nominally took Cardiff East from the Conservatives but lost it to Labour in the 1945 general election.
18. ^¹ Southampton was a two-member constituency. In the 1935 general election it elected one National Liberal and one non-party supporter of the National Government. In February 1940 Sir John Reith (the newly appointed Minister of Information) was elected unopposed to fill a National Liberal vacancy as a non-party supporter of the National Government. In November 1940 he was elevated to the peerage and in the resulting unopposed by-election his seat was regained by the National Liberals. In the 1945 general election both seats were won by the Labour Party.
19. ^Headlam was elected as the nominee of a breakaway Conservative Association who opposed the selection of the official candidate. In Parliament he took the Conservative whip and retained the seat as an official Conservative in the 1945 general election.
20. ^The Times, 20 February 1940, page 5
21. ^Cambridge University was a two-member constituency. In the 1935 general election it elected two Conservative MPs. Hill took one seat from the Conservatives as an Independent Conservative, but did not contest 1945 general election, in which the two seats were won by one Conservative and one Independent.
22. ^¹ The City of London was a two member constituency. In the 1935 general election it elected two Conservative MPs. In February 1940 Sir Andrew Duncan (the newly appointed President of the Board of Trade) was elected unopposed to fill one vacancy as a non-party supporter of the National Government. In the 1945 general election Duncan and a Conservative won the City's two seats.
23. ^The Duchess of Atholl had resigned the National Government whip over foreign policy and in November 1938 was deselected as a candidate by her local association. She decided to resign her seat and fight a by-election as an Independent in opposition to the policy of appeasement. She lost the seat to the new Conservative candidate.
24. ^In 1942 Bartlett co-founded the Common Wealth Party and served on its National Committee, but resigned two months later and reverted to being an Independent Progressive MP, retaining the seat in his original colours in the 1945 general election.
25. ^The Dartford county constituency was divided in a mini redistribution in 1945 into two borough constituencies - Bexley and Dartford. Labour upheld its by-election gain in both constituencies with Adamson carrying the Bexley seat.
26. ^Lipson was elected as an Independent Conservative but in Parliament supported the National Government. He was re-elected in the 1945 general election as an independent supporter of Churchill's government.
27. ^The Combined English Universities was a two-member constituency. In the 1935 general election it elected one Conservative and one Independent (Eleanor Rathbone). Harvey took the seat from the Conservatives as an "Independent Progressive" but did not contest the 1945 general election which was won by two Independents (Rathbone and K.M. Lindsay).
28. ^^{1 2 3 4 5 6 7 8 9} An uncontested by-election.
29. ^^{1 2 3 4 5 6 7} Gain retained at the 1935 general election.
30. ^{{London Gazette|issue=34175|page=4160|date=28 June 1935}}
31. ^^1 2 Gain not retained at the 1935 UK general election.