 The City of Peterborough formed a parliamentary borough returning two Members in 1541. The rest of the Soke of Peterborough was part of the Northamptonshire parliamentary county, except the area south of the River Nene in the historic county of Huntingdonshire and Thorney, which was considered part of Cambridgeshire. Until 1832 when the whole of the parish of Saint John the Baptist was encompassed, the boundary, as far as is known, excluded the villages of Longthorpe, Dogsthorpe and Newark with Eastfield. The Great Reform Act did not affect the borough, while the rural portion of the Soke was included in the northern division of Northamptonshire. New Fletton was transferred from Huntingdonshire in 1868 and in 1918 the parliamentary borough was abolished and replaced with a new division of the parliamentary county of Northampton with the Soke of Peterborough, including the whole of the Soke and neighbouring parts of the administrative county of Northamptonshire, extending down to and beyond Thrapston and Corby. This became a county constituency under the 1948 revisions, when the boundaries of the constituency were adjusted to correspond to those of the Soke and they remained much the same until 1970. Peterborough became a county constituency in 1974.
