From 1835 parishes were combined into poor law unions, and they were allowed to spread the cost of building and running a workhouse between them. The late 1830s therefore saw a large number of institutions being built. At the time, these were state-of-the-art, clean, smart buildings; only later did they decay into the grim institutions we read about in Dickens.
Huntingdonshire
Three such workhouses were built in Huntingdonshire - one in Great Stukeley to serve the Huntingdon Union area, one in Hemingford Grey to serve the St Ives Union, and one just across the river from St Neots.
Huntingdonshire Archives has superb collections of records for the Huntingdon and St Ives workhouses, including registers of admissions and discharges, birth and death registers, punishment books, and occasionally plans. Much less survives for the St Neots workhouse, sadly.
Cambridgeshire
Records here include a number concerning inmates; such as registers of births, deaths, creeds and punishments; plans of the workhouse buildings and the records of other workhouse officers, like the Master or medical officer. The Cambridge Union records also include a number of Settlement papers while the Caxton records include account books for alcohol and tobacco as well as registers of “seclusion and mechanical restraint”. Many of these records do not offer complete coverage for the lifetime of the workhouse; a full list of the records for post-1834 workhouses can be found in the Poor Law Unions catalogue on the searchroom shelf.
There is an excellent book about the setting up of Huntingdonshire and Cambridgeshire's workhouses, In and Out of the Workhouse (WEA, 1978), which is available in both searchrooms.
Census returns are also a valuable source as they provide a list of those in the workhouse on enumeration night.