I don't think this all over pale barley-sugar was a T/Webb colour, and although the factory didn't always use a backstamp, that flat bottom doesn't look very T/Webb ish to me. The majority of handled custards seem to have had stems of some sort, but there were a percentage without, so you may be correct. Decoration aside, ninety odd percent of custards seem to be clear, with the odd one in cranberry, and only very rarely do other colours occur, but I have them in a sort of amber/brown. This looks to be about mid C20 or perhaps a tad earlier.
sorry, not very helpful.