I've been reading a book about the RN in the later Victorian period (From Warrior to Dreadnought, by DK Brown) I notice that in some of the photos dating from between (I would guess) 1880 and the beginning of WW1 the ships are wearing a union flag on the foremast with the ship under way. In one case it is being flown inferior to a vice-admiral's flag. Now, I seem to remember that the union flag being flown on a mast, as opposed to the jackstaff, signifies either that a court martial is taking place on board, or that an admiral of the fleet is flying his flag. Neither seems likely in these cases. Any bunting-tosser out there who knows what it signifies?