| Election Name: | 1975 Woolwich West by-election |
| Type: | parliamentary |
| Country: | United Kingdom |
| Seats For Election: | Constituency of Woolwich West |
| Ongoing: | no |
| Previous Election: | October 1974 United Kingdom general election |
| Previous Year: | Oct. 1974 |
| Next Election: | 1979 United Kingdom general election |
| Next Year: | 1979 |
| Election Date: | 26 June 1975 |
| Candidate1: | Peter Bottomley |
| Party1: | Conservative Party (UK) |
| Popular Vote1: | 17,280 |
| Percentage1: | 48.78% |
| Swing1: | 10.19% |
| Candidate2: | Joseph Stanyer |
| Party2: | Labour Party (UK) |
| Popular Vote2: | 14,898 |
| Percentage2: | 42.06% |
| Swing2: | 5.03% |
| Candidate3: | Sheilagh Hobday |
| Image3: | Lib |
| Party3: | Liberal Party (UK) |
| Popular Vote3: | 1,884 |
| Percentage3: | 5.32% |
| Swing3: | 8.99% |
| MP | |
| Before Election: | William Hamling |
| Before Party: | Labour Party (UK) |
| After Election: | Peter Bottomley |
| After Party: | Conservative Party (UK) |
| Turnout: | 46.43% (27.46%) |
The 1975 Woolwich West by-election was a parliamentary by-election held on 26 June 1975 for the British House of Commons constituency of Woolwich West in South East London.
This was the first by-election since the general election the previous October.[1] The seat had become vacant when the constituency's Labour Member of Parliament (MP), William Hamling, died on 20 March 1975. He had held the seat since winning it from the Conservatives at the 1964 general election.
The result of the contest was a victory for the Conservative candidate, Peter Bottomley, who held the seat until its abolition for the 1983 general election; he had contested the seat in both 1974 general elections. He then sat for Eltham, the successor seat, and from 1997 to 2024 represented Worthing West, formerly a safe Conservative seat in West Sussex.
The result reduced the Labour majority in the House of Commons from three seats to one seat, the Labour total falling from 319 to 318 in a House of 635 members. However, the position of the Labour Government was made worse by the fact that one of its MPs, John Stonehouse, was absent from the country.[1]
This was the first by-election the Conservatives fought under the leadership of Margaret Thatcher, who, by personally canvassing in support of Bottomley, abandoned a convention that party leaders did not campaign in by-elections.[1] Writing in The Glasgow Herald, political correspondent John Warden stated that the victory would boost Thatcher by silencing "mutterings about her leadership" for at least a few months.[1]