Inland county in eastern England, much enlarged in 1974; it is usually regarded as one of the counties of East Anglia. A great part of the original county belonged to the Fenlands.
The Fens lay within the area held by the Danes in the late 9th/early 10th centuries when Cambridge was the meeting place for the settlers and rallying point in time of emergency. After it had become an English shire Cambridgeshire was in practice administratively divided for many years. The northern part of the county, the Isle of Ely, in the midst of the Fens, was held by the Abbey of Ely, which became the cathedral church of a new Bishopric in 1109. The Abbey, and later the Bishop, held the Isle of Ely as a franchise; the King’s sheriff in Cambridgeshire had no authority there.
In the reign of Henry VIII, most of the various areas of the Kingdom that stood in part outside royal authority had their anomalous rights curtailed. So it was with Ely, though the Bishop and his officers retained some limited rights until the 19th century.
Even so, the Isle of Ely continued to have its own treasurer and rate, separate from Cambridgeshire (indeed it actually had two treasurers and two separate rates), with the result that when elected county councils were created by the Act of 1888, Cambridgeshire had two of them, Cambridgeshire in the south and the Isle of Ely in the north. In 1965 the two councils were amalgamated and Cambridgeshire (or Cambridgeshire & the Isle of Ely) formed one administrative as well as one geographic county.
By the Local Government Act of 1972 Cambridgeshire was merged in 1974 with the county of Huntingdon & Peterborough, itself the amalgamation (in 1965) of two administrative counties, those of Huntingdonshire and the Soke of Peterborough. The union of Cambridgeshire and Huntingdonshire was in one respect long anticipated in that the two counties had always had a common sheriff, except in the Norman era and for a few years in the 17th century.
This common sheriffdom is perhaps the reason why there is only one Earl of Cambridge before 1340, created in 1139, and he almost immediately transferred to Lincoln. In 1340 the King’s brother-in-law, William, Count of Jülich, became Earl and thereafter as Earldom, Dukedom or Marquisate, Cambridge has been a royal title, except between 1619 and 1651, when it provided an English Earldom for a Scottish Marquis (Hamilton).
The saddest holders of its several titles were four infant sons of the future James II, each elevated to the Dukedom not long before being lowered to the grave. The most recent creation was a Marquisate for Alexander, Duke of Teck, the brother-in-law of George V, when he gave up his German titles in 1917. Cambridge provided him, and his son and only successor, with both a peerage and a surname.
The new Cambridgeshire of 1974, with one county council responsible for an area that had been governed by four county councils ten years previously, had added rather more than half again to its area in that year, and it advanced from 29th in area of the counties of England to 17th. Its population, which increased even more in absolute numbers (by about three quarters), advanced relatively less, from 37th to 32nd, but then one purpose of the 1972 reform was to increase the population of the less populous counties.
Cambridgeshire became a hybrid county in 1998 when the city of Peterborough became a unitary authority, the rest of the county keeping two-tier government. There had been no county boroughs before 1974, Cambridge’s efforts in earlier years having always been frustrated. To have removed Cambridge from the small administrative county of 1888-1965 would have greatly weakened the county council.