In Alistair's material was a cover with a censorship label reading OPENED FOR THE CENSOR.
It is addressed to Military Tailors at Winchester. 
The 1d stamp and its postmark 28 Dec 14 both cover the label.
The place of the postmark is not too clear but I think it is Chelsea.
Clearly this is not censorship of civil mail as the label does not match anything recorded by civil censorship specialists and because the postage stamp and postmark are over the label.
It does not appear to be naval as the addressee is "Military Tailors" and Winchester being an important garrison city.
Has anyone seen anything similar to this please?
I have not found any mention of this in the Journal or Newsletter.
Graham Mark