On the question of moustaches in the RN,, this was debated in Parliament on Friday 27th November 1914 when Mr. WILLIAM THORNE asked the First Lord of the Admiralty, if it has been the custom to allow the men serving in the Royal Fleet Naval Reserve to wear a moustache; if he is aware that an order has just been given out that those men must shave off their moustaches; and if he intends taking any action in the matter?
Dr. MACNAMARA replied that the wearing of a moustache only is forbidden by the King’s Regulations, but this is not usually enforced in the case of Reserve men during peace. On being “called out” they become a part of the Navy proper, and as such would be expected to conform to the Regulations of the Service. If the men objected to shaving their moustaches, they are at liberty to discontinue the use of the razor altogether.
The conclusion is that the photo shows Reservists sporting moustaches before they were called up, i.e before August 1914. Whether they were Fleet Reservists or RNR is not known.