In 1641 Parliament organised a national protest against Charles I's style of government. All men aged 18 or above were required to sign a declaration of belief in the Protestant faith, and declare support for Parliament's rights and privileges. Most surviving returns (many were destroyed in the 1834 Houses of Parliament fire) are now held at the Parliamentary Archives.
Huntingdonshire
The protestation returns for Huntingdonshire were printed with an introduction by Granville Proby in Transactions of the Cambridgeshire and Huntingdonshire Archaeological Society vol 5 (1937). An index was compiled in 1981 by Ray Waymont. Both of these works are now available in the searchroom library at Huntingdonshire Archives.
Cambridgeshire
The only Protestation Returns surviving for Cambridgeshire and the Isle of Ely are for the University of Cambridge. These are held at the Parliamentary Archives [HL/PO/JO/10/1/78] and have been transcribed and indexed by Pamela Palgrave. A copy is available at the Cambridgeshire Collection.