I have posted a reply on Dave's query about Hursley Park POW camp near Winchester which includes details of inspection reports of most of the POW camps in Britain by the Swiss legation in London in the Foreign Office files (see link here Legation reports
There are a couple of large images attached to show examples and a link to the website at Kew for an example. These reports are quite detailed and give locations, numbers of prisoners reports on facilities grievances etc. most seem to date from 1917 onwards
Skipping through the rest of the sub-forum I see they haven't been mentioned before so I thought I would flag them up. I can post somemore examples if anybody is interested (mainly of Dorset, Wiltshire camps which I am interested in)? I havent looked at all the files yet??!!