WR for intelliegence it seems these will be the places to start with:-
Naval Intelligence Records
A collection of reports and papers of the Naval Intelligence Division (N.I.D.) is in ADM 223 . In addition to texts of early decrypts of German naval wireless traffic encyphered on the ENIGMA machine, there are reports and summaries, both from N.I.D. and the Operational Intelligence Centre (O.I.C.), based on this 'Special Intelligence'. These reports include: O.I.C. Daily Reports up to September 1940 (ADM 223/79-83 ) and O.I.C. Special Intelligence Summaries from 1940 onwards (ADM 223/8-24 , 43-50 , 92-101 , 170-175 , 310-314 , 321-329 ). It should be noted that selected documents relating to ENIGMA and the Battle of the Atlantic from this series have been transcribed and published in two volumes for the Navy Records Society (The Battle of the Atlantic and Signals Intelligence, ed D Syrett, Navy Records Society, 139 and 144, 1998, 2002).
See below, note high prices!
http://www.amazon.co.uk/s/ref=nb_ss_b/203-2419741-3979107?url=search-alias%3Dstripbooks&field-keywords=The+Battle+of+the+Atlantic+and+Signals+Intelligence&Go.x=4&Go.y=12
Other records in ADM 223 include more general daily and weekly intelligence summaries (ADM 223/146-169 , 830-834 , 852-863 ), 'operational packs' regarding particular engagements and operations (ADM 223/332-342 , 507-619 , 676-686 , 697 ), and photocopies of documents not yet transferred, but cited in the footnotes of Volume 1 of The Official History of British Intelligence in the War (ADM 223/84-86 , 107-108 , 209 , 212-214 ). DEFE 3 (Admiralty: Operational Intelligence Centre: Intelligence from Intercepted German, Italian and Japanese Radio Communications, WWII) contains the texts of enemy signals, both naval and other, decrypted by the Government Code and Cypher School. HW 1 Government Code and Cypher School: Signals Intelligence Passed to the Prime Minister, Messages and Correspondence
I've found some camouflage stuff in here also that might interest:-
ADM 212/98 Dazzle Sub-Committee of Vision Committee: progress report 1942
ADM 212/121 Notes on structional camouflage of battle class destroyers and MTB's 1942
ADM 212/122 Camouflage of merchant ships: notes on tests made at Leamington viewing tank 1942
ADM 212/123 Report on camouflage observation trials in the Scapa area 1942
ADM 212/124 Standardisation of Admiralty camouflage colours 1942
ADM 212/125 German camouflage: apparatus for measuring optical properties of sea water 1942
ADM 212/126 Uniform camouflage design: notes and correspondence 1942-44
ADM 212/127 Survey report by Lieut Pyes on light toned camouflage in North Atlantic 1943
ADM 212/128 Quantitative assessment of painted camouflage 1942-48
ADM 212/129 Camouflage of ships against land backgrounds: note on Umbrella experiment 1942-44
ADM 212/130 Camouflage colours HM Australian ships 1943
ADM 212/131 Report on trial of camouflage paint from HM Dockyard Portsmouth 1943
ADM 212/132 Correspondence, papers and photographs concerning concealment of ships at sea 1943-44
ADM 212/133 Investigations into visibility of submerged submarines 1944
ADM 212/134 German camouflage of ships: reports and photographs 1944
ADM 212/135 Notes on the effect of countershading camouflage 1944
ADM 212/136 Influence of angle of incidence of light on ships appearance 1945
ADM 212/137 American camouflage trials: notes by Director of Scientific Research 1945
ADM 212/138 Visibility of targets, effect of directional lighting 1945
Have you looked at any of the above in the 1960/70s???
Or are these titles new to you?
Another grey area I've not seen anything published on:-
ADM 212/194 Notes on 50 years of research: infra-red, 1938-1945 covering date c1971
Yes the PRO truely is a treasure trove!