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.

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.

[4] 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.