The blue top mark was used on all British Royal Navy dinnerware from about 1937 onward. The majority I have date to the 1960's.
Vintage Royal Navy Mess Plate Admiralty, 1960's, Ceramic
Vintage Royal Navy Mess Coffee Can Cup & Saucer, Admiralty, 1950-60's, Ceramic
Authentic WWII British Royal Navy Mess Bowl VOC 52105 MMS 1940 Nautical Antique
Vintage Royal Navy posters HMS Ark Royal HMS Swiftsure HMS Briliant HMS Spartan
Vintage Royal Navy HMY Brittania Wall Plaque VGC
Vintage Royal Navy Boatswain Whistle Bosuns Pipe Call with Broad Arrow