Unfortunately for the spoon collector, date marks for provincial assay towns rarely appeared on small spoons (e.g. tea and mustard) until the early 19th century, and it was only common practice by 1821! I'm afraid Will, that your spoon was assayed in Newcastle, as Waylander said, which is a provincial assay town. I have a Dorothy Langlands teaspoon (Newcastle) with no date, so I can empathize with your situation.
Waylander, did you arrive at your 1821-39 date based on the lack of cusping on the duty mark? The collector can't even use this valuable tool, because cusping was not used on the duty marks of small spoons in Newcastle. I disagree with your 1821-39 because, as I mentioned above, by that time date marks were being used on small spoons, and also the rapid broadening of the handle suggests a date much nearer the turn of the century.
I had never heard of George Murray before, so I looked him up and found one mark of his from 1810 which I think is fairly similar to this one, though there are some differences (sorry for the poor quality). You'll notice the order of the hallmarks: maker-town-lion-duty which was the practice from 1798-1815 (although not exclusively).
In conclusion I believe the maker was (as suggested by Waylander) George Murray and was made 1805-1810.
Mike (georgiansilver), I would love to hear your opinion on this piece.