The county was represented by two Knights of the Shire until 1832, when the number of members was increased to three by the Great Reform Act. Under the Redistribution of Seats Act 1885, the constituency was abolished and was divided into three single-member constituencies: the Western or Chesterton Division, the Eastern or Newmarket Division and the Northern or Wisbech Division.
Under the Local Government Act 1888, the historic county of Cambridgeshire was divided between the administrative counties of Cambridgeshire and Isle of Ely. When the parliamentary constituencies were next redistributed under the Representation of the People Act 1918, Cambridgeshire was re-constituted as a single-member Parliamentary County, largely formed from combining the Chesterton Division (excluding areas that were now part of the expanded Municipal Borough of Cambridge) and the Newmarket Division (excluding the city of Ely which was included in the Parliamentary County of Isle of Ely).
The administrative counties of Cambridgeshire and Isle of Ely had been recombined in 1965 and Cambridgeshire was further expanded in 1974 to include Huntingdon and Peterborough under the Local Government Act 1972. Under the subsequent redistribution of seats, which did not come into effect until the 1983 general election, Cambridgeshire was abolished as a county constituency, forming the bulk of the new constituency of South East Cambridgeshire and the majority of South West Cambridgeshire.
1290–1653, 1658-1885: The historic county of Cambridgeshire. (Although Cambridgeshire contained the borough of Cambridge, which elected two MPs in its own right, this was not excluded from the county constituency, and owning property within the borough could confer a vote at the county election. In the elections of 1830 and 1831, about an eighth of the votes cast for the county came from within Cambridge itself. The city of Ely also elected its own MPs in 1295.)
1654–1658: The historic county was divided for the First and the Second Protectorate Parliaments, between the two-member Isle of Ely area and the four-member constituency consisting of the rest of the county.
There were minor boundary changes in 1950, when some of the constituency was transferred to the Cambridge seat, which was expanded to align with the Municipal Borough, and in 1974, to align with changes to the county boundary.
^S., Craig, Fred W. (1972). Boundaries of parliamentary constituencies 1885-1972;. Chichester: Political Reference Publications. ISBN0900178094. OCLC539011.{{cite book}}: CS1 maint: multiple names: authors list (link)