my first thoughts would also have been S. & W. rose alabaster, although not aware of this sort of graduated colouring in S. & W. pieces - so I'd plump for this not being theirs.
Although Nazeing did do a posy vase with this type of 'pinched in' rim, the rest of this piece doesn't match with theirs, and can't find any other Nazeing shape, in the book, that is similar.
Purely as an uneducated guess, this colourway doesn't ring any bells with any Elwell material I've seen, but not really my area.
Must confess my ignorance in that I didn't know that S. & W. made pieces for Elwell - Roberta, are you able to point me in the direction of any images - would be interested to see some of those pieces.

Geoff. Timberlake's book comments that "One of his daughters stated that he also bought from Gary Stan, Whitefriars, Stuart, Thomas Webb and Czechoslovakian factories".