Just one of the pieces in my collection which are all certificated.

This one is the Pussers [Royal Naval] clock which adorned the captain's bridge in our last battleship, HMS Vanguard.  Our capital and major warships, including cruisers, were all capable of acting as a flagship* and thus had accommodation for an admiral and his staff which included an admiral's bridge, quite separate to that of the ship's or captain's bridge. Admiralty naval stores item number was 0552/461-9413.

My collection was purchased from Flemings of Southsea, Hampshire, UK over a period of approximately six years.  Flemings [not to be confused with the naval tailors of the same name and same trading period although they were in Queens Street in nearby Portsmouth] were high profile buyers of ex-Admiralty equipments and everything they sold worked and was in excellent condition, often brand new. What they offered was sold on a 'first see-first buy' basis without privilege, pomp or circumstance! If you could pay the asking price, it was yours. 

* In the 1970's [and at other times too] smaller ships were used as flagships and these included mainly the heavy destroyers, the GMD's [or DLG's] plus HMS Bristol a type 82 destroyer. However, I experienced several flagships whilst on the staff of Rear Admiral [Whisky - the admiral was a Scot] Wemyss {Rear Admiral Martin La Touche Wemyss} FOF2, and I can assure you that 'comfort and facilities' meant either the cruiser Tiger or Blake. Of the other big ships, LPD's, LPH's and fixed-wing Carriers, these acted as flagships to FOCAS [Flag Officer Carriers Assault Ships].