The 1971 Greenwich by-election of 8 July 1971 was held after the Labour Member of Parliament (MP) Richard Marsh, resigned from the House of Commons to take up the post of Chairman of British Rail. The seat was retained by Labour.
| Party | Candidate | Votes | % | ±% | |
|---|---|---|---|---|---|
| Labour | Guy Barnett | 14,671 | 66.73 | +10.98 | |
| Conservative | J Stuart Thom | 6,150 | 27.97 | -7.39 | |
| Fellowship | Ronald Mallone | 792 | 3.60 | New | |
| Ind. Conservative | Reginald Simmerson | 285 | 1.30 | New | |
| Independent | David Davies | 89 | 0.40 | New | |
| Majority | 8,521 | 38.76 | +18.37 | ||
| Turnout | 21,987 | ||||
| Labour hold | Swing | ||||
| Party | Candidate | Votes | % | ±% | |
|---|---|---|---|---|---|
| Labour | Richard Marsh | 20,804 | 55.75 | -9.11 | |
| Conservative | J Stuart Thom | 13,195 | 35.36 | +0.22 | |
| Liberal | P. Wylan | 3,319 | 8.89 | New | |
| Majority | 7,609 | 20.39 | -7.33 | ||
| Turnout | 37,318 | 65.66 | -2.04 | ||
| Labour hold | Swing | -4.67 | |||