| Election Name: | 1982 Birmingham Northfield by-election |
| Type: | parliamentary |
| Country: | United Kingdom |
| Seats For Election: | Constituency of Birmingham Northfield |
| Ongoing: | no |
| Previous Election: | 1979 United Kingdom general election |
| Previous Year: | 1979 |
| Next Election: | 1983 United Kingdom general election |
| Next Year: | 1983 |
| Election Date: | 28 October 1982 |
| Candidate1: | John Spellar |
| Party1: | Labour Party (UK) |
| Popular Vote1: | 15,904 |
| Percentage1: | 36.3% |
| Swing1: | 8.8% |
| Candidate2: | Roger Gale |
| Party2: | Conservative Party (UK) |
| Popular Vote2: | 15,615 |
| Percentage2: | 35.6% |
| Swing2: | 9.8% |
| Candidate3: | Stephen Ridley |
| Image3: | Lib |
| Party3: | Liberal Party (UK) |
| Popular Vote3: | 11,453 |
| Percentage3: | 26.1% |
| Swing3: | 18.0% |
| Map Size: | 200px |
| MP | |
| Before Election: | Jocelyn Cadbury |
| Before Party: | Conservative Party (UK) |
| After Election: | John Spellar |
| After Party: | Labour Party (UK) |
| Turnout: | 55.0% |
The Birmingham, Northfield by-election of 28 October 1982 was held after the death of Conservative Member of Parliament (MP) Jocelyn Cadbury on 31 July 1982. The seat was gained by the Labour Party in a defeat for Margaret Thatcher's government, ironically just after opinion polls showed an upswing in Conservative support following the victorious Falklands War campaign months earlier. The Conservatives regained the seat at the 1983 general election.
The result gave the Labour Party its first gain in a by-election in Britain since 1971. Yet while Labour had regained the seat which it had lost in 1979, the Conservatives were reported to be delighted at only narrowly losing given that the seat had been their third most vulnerable based on the 1979 results. Norman Tebbit, then a Conservative Cabinet minister, noted his party had come "within an ace of holding one of our most marginal constituencies" and argued that the results in Northfield and the by-election held on the same day for the Peckham constituency showed that the intervention of the Alliance allowed Labour to win.[3] Writing in The Glasgow Herald, political journalist Geoffrey Parkhouse argued that winning Northfield saved Labour leader Michael Foot "from disaster", but the closeness of the result meant it was a "desperate victory" for him. He also argued that the results showed that Margaret Thatcher's government was on course to win the next election, but that the Alliance's potential to take votes from the Conservatives could yet prevent them from gaining an overall majority.[3]