The late Peter Hodges, writing in 'Royal Navy Warship Camouflage, 1939-45' (Almark, 1973) says:

'some ships were not 'camouflaged' at all but remained painted an overall grey. ... the Alternative Scheme to the Admiralty Intermediate pattern was, in fact, overall mid-grey, but since grey itself was used as a means of providing some means of concealment, it can fairly said to be a 'camouflage' scheme in its own right' (p36).

(Despite its age, copies are available on the www)

TH