A British Prisoner was said to have been informed by the Commandant of Doberitz POW camp of his award of the Victoria Cross..Where would I start to look for records from this camp ?
The Deutsche Dienststelle (WASt) holds
Approximately 1.500.000 files (residue) on foreign P.o.Ws. in German custody. (Assets of the Deutsche Dienststelle)
I wrote a little bit on using records from the Deutsche Dienststelle in my answer to How to find information on German soldiers from World War I and World War II?. In a nutshell: You’ll send a request using the online form (available in German, English and French). You have to pay at least 8 Euro per answer page and wait for up to a year. They will answer you in German. You should give it a try.
The archives of the International Prisoners-of-War Agency are now available. They hold 500,000 pages of lists and six million index cards regarding prisoners of war (WW I).
Please see also The National Archives: Looking for records of a British prisoner of war c.1790-1919 for a general overview.
I can’t comment on military sources in Britain, but I have serious doubts that there are other archives in Germany beside the Deutsche Dienststelle holding individual records.
When searching the internet for the camp refer to the query Gefangenenlager Döberitz for German results. Martin Conrath published several documents on the history of the Döberitzer Heide (Zur Geschichte der Döberitzer Heide), which can be found online and also contain information on the German barracks and POW camps. Maybe you’ll discover your ancestor or his name somewhere. See also The Döberitz Gazette: An International Magazine for the Kriegsgefangene Interned at Döberitz. Additional information on this publication are available on doberitz.com