| Mayo West |
|
| Meath |
|
| Meath North |
|
| Meath South |
|
| Medway |
Full name (in Craig 2) Kent, Medway |
| Meirionnydd Nant Conwy |
|
| Melton |
Full name (in Craig 2,3,4) Leicestershire, Melton |
| Meon Valley |
This seat has been formed by the Boundary Commission for England as an extra constituency in Hampshire |
| Meriden |
Full name (in Craig 4) Warwickshire, Meriden |
| Merioneth |
|
| Merionethshire |
|
| Merthyr Tydfil |
Constituency of same name also existed 1832-1918. |
| Merthyr Tydfil |
Constituency of same name also existed 1950-1983. |
| Merthyr Tydfil Aberdare |
|
| Merthyr Tydfil and Rhymney |
|
| Merthyr Tydfil Merthyr |
|
| Merton and Morden |
|
| Merton Mitcham and Morden |
|
| Middlesbrough |
Seat of same name existed 1832-1918. |
| Middlesbrough |
Seat of same name reformed 1983. |