A pair of green opalescent Sowerby pattern 1240 ‘Gladstone bags’ which appears on page 4 of their pattern book IX (1882). There are from registered design number 314283, registered on 18 September 1877. The opalescence is mainly toards the base of the pieces, and I am told that the glass is not UV-reactive.
(Permission for the re-use of these images on the GMB granted by glassmahonia).
Usually seen in blue or purple malachite or plain black vitro-porcelain, these are the first opalescent green versions I have seen.
The only other opalescent versions I know of are a pair of rose opalescent examples in the Shipley Art Gallery (and which are shown in the pattern number gallery in the final section of Vol. 3 of the Thistlewood Sowerby CD-ROM catalogues).
Someone must value these green opalescent versions highly too, because they reached a final bid price of £292.82 after a frenetic final few seconds of bidding on eBay tonight.
Fred.