There are three particularly useful links:
Look for UK POW Camp forum. Set-up by Pete Wood – an ideal place to request/give information.
Site by Martin J Richards. Martin is a professional photographer who has produced many stunning images of pow camps as they are today.
The essential information source for u-boats and their crews – many of whom were held in pow camps in the UK.
NUMBERS – each camp was assigned a number. These were different for each camp at any one time, but over time they changed for various reasons. ‘Modern’ lists combine these changes which makes it appear that different camps had the same number at the same time. For example, when Kirkwall Camp 165 on Orkney closed down, then the newly opening Watten Camp was assigned that number. Also, when Wilton Park Camp (300) changed to a special camp, its number changed to Camp 20.
Camp lists – In 1939 there were just 2 camps – Grizedale and Glen Mills, (see memorandum by the Foreign Secretary 18 Dec 1939, WP(G) (39) 157)). There was also the ‘Combined Services Detailed Interrogation Centre’ at the Tower of London until December 1939.
At the end of 1940 a statement to the War Cabinet detailed 11 pow camps and 1 hospital, (Appendix to WO 199/405). However, the list omitted Duff House Camp 5.
The International Red Cross Committee (ICRC) in Geneva, received regular updates of the camp list from the Prisoner of War Information Bureau (PWIB). The list from Autumn 1945 has been included for each camp that existed at that time.
Another list by the PWIB created in February, 1947 was used by the special camp at Wilton Park – this has also been included. Details listed were: Camp number, Address, Command area, Telegraphic address, Telephone number, Railway station, Commandant, and the War Establishment code.
I would very much like to find further PWIB lists.
English Heritage produced a project report in 2003, which is an extremely useful source of basic information. Details included condition (1 complete / 2 near complete / 3 partial remains / 4 demolished / 5 Unresolved), Type in 1945, and comments. NOTE, that type only refers to 1945, many camps changed their status over time.
DETAILS IN RED ARE UNCERTAIN!