I seem to recall seeing brown coloured example very recently in a similar outlet, and if you look at this link.....
http://www.glassmessages.com/index.php/topic,52111.msg296763.html#msg296763 ..... you'll see that Mel also had a blue/sapphire tankard that appears to be the same as this one.
And if you look here..........
http://www.glassmessages.com/index.php/topic,51074.msg289424.html#msg289424 ....... there is another blue/sapphire tumbler with the same pattern, and I think one or two folk have had these in recent times - so the conclusion is that they're fairly common.
They seem to have been dismissed, regularly, as W/Fs. on the basis of the curved swags from that factory, as opposed to the sharper pointed lines of T/Webb's Ribbonette, which was my suggetion - see CH (1800 - 1914), which shows Ribbonette pattern on page 433 - but despite my enthusiasm for this provenance regret it's not conclusive until we find the backstamp on something.
Somewhere in the above links I've shown what I believe to be a Ribbonette patterned brown tumbler (I have a short set of four) - and although none is marked, they have a striking overall similarity of shape to another marked set of T/Webb uranium tumblers I have - hence my opinion in making the connection with Ribbonette.
There are some striking similarities between these marked and unmarked tumblers............... the type of pontil depression is identical - the size and flared rims are the same. Unfortunately, there are differences.............. slight difference in thickness of glass, and the marked examples 'ring' when flicked, whereas the others don't.
I believe Nigel has also commented that he's not been aware of seeing a backstamp on this pointed pattern - and the same must be true for Bernard - otherwise he would have commented.
Glass from T/Webb is not always marked, although by the law of averages I'd have expected at least one of these pointed swagged pieces to have been found showing their backstamp - but it seems that so far this has not happened, and this may lean in favour of Bernard's comments. But if someone does have a backstamp on a pointed swagged piece do shout.
CH's book includes a variety of T/Webb optic patterns, and Ribbonette (1910 in origin) is the only one I'm aware of that shows pointed swags, and an absence of any curve to the design. This isn't conclusive, so it looks as though the jury remains out. Not to be confused with T/Webb's Wave pattern.
My own opinion would be that it's not Stuart, although that factory did produce a very similar blue. Whatever the origin of this pattern, it seems to surface regularly in the shape of water jugs, tumblers and tankards. Anyone know of other shapes?
Apologise if my links have crossed with the information provided in Bernard's.