Thomas I'm sure you have far more references than I, and this is probably not all that helpful, but in CH 20th CenturyBritish Glass page 33, there is a plate of hock glasses, one of which is similar colours to yours - the blurb underneath does mention '...Harry Whitworth who joined the firm as an engraver in 1916, is recorded as decorating a Rockinghan cased on citron hock glass in 1918'.
I have no idea what 'Rockingham' means or whether the dates fit in, but it may be another name to search for?
m