If you look at page 67 in Miller's/McConnell '20th Century Glass', you'll see an amber version of this piece. The caption indicates that 'the addition of the word celery enabled this Thomas Webb vase to be categorized as utility glass, so avoiding the outright ban on sales of fancy glass in Britain between 1942 and 1952'. Then the situation changed and for the years 1952 to 1955 a 100% luxury tax was imposed, which after 1955 was reduced to 30%.
As a general shape, this looks much like other T/Webb optically moulded designs that had been around since the 1930's - sort of art deco flared rim and large foot - and the backstamp on this particular vase shows what the books describe as the mark for 1950 - 1966.
This clear example is without the word celery - and presumably wasn't the sort of item that you want to pay 100% tax on, so I can imagine it being made/sold after 1955. If anyone has other ideas please shout, and thanks for looking