Hello Chris .. I'd suggest a claret decanter, if only because of the stopper........the jugs don't usually have a stopper.
This is a high quality piece - and if you're correct re the upper case M, then I believe this date code is for 1947/48.
From what I can see, most of the decoration is wheel engraved i.e. much more shallow than the sort of cuts produced by standard glass cutting - these effects are produced usually by small copper wheels of varying sizes. However, the large curved swags would probably be more like ordinary glass cutting - deep and fairly wide.
I've attached couple of pix to show very similar work produced by the Stourbridge Glass Co. (who later became Tuder Crystal I think) - and you can see, especially in the second pic, the swags (like yours) created using circular disc like impression of graded size.
Your piece may well have been engraved by someone like Jack Lloyd, who continued working until the 1970's - having been with both companies I think. Do check carefully to see if there is a small signature somewhere on the body, also look for 'matching Nos.' - the factory's method at time of manufacture, as a way of keeping stoppers with the correct fitting body. Small Nos., possibly on the stubb of the stopper, also somewhere on the neck of the body.
