Speaking of the Roger Dodsworth edited 'BRITISH GLASS between the wars' softback book, Bernard Cavelot commented some years back "Ignore the section on Webb Corbett acid-etched marks and their dates."
Exactly why he considered we should be wary of the dates given, he didn't say, and now of course we can't ask ask him - I suspect it likely he felt they needed wider or smaller margins, or similar, but that's just my opinion.
There are plenty of pieces from this factory where the backstamp includes the letters T and S, indicating the place of manufacture as either Tutbury Stourbridge, but far fewer that have the earlier 1930 - 47 (according to Dodsworth) crescent shaped mark that lacks this indication of origin.
So, pleased to find the tumbler shown - a lightweight almost aesthetic looking design that made me think 1930s - delicate curves and about as far removed from the dreaded criss-cross of geometric mitres as you can imagine.
I've rummaged through a variety of books, but the only one I can find where this design is shown is Nigel Benson's 'ART DECO TO POST MODERNISM' - page 27 - item 126....... albeit a very small illustration, but I'm sure this is a match.
Nigel describes this design as follows......... "........cut all over with geometric squares & loops, attributed to John Webb, marked Webb Corbett Made in England, c. 1940 ... Illustrated PG>R April 1940 under the section "Britain can Export" feature. For how long the design was offered by the factory I've no idea. Apologies that the attached picture of the backstamp is very poor - I did try talc but hardly any improvement.
One of my better charity shop finds last week - all I need now is ......... the decanter, the vase, the water jug and stemmed drinking glass