Unfortunately, Stuart Crystal no longer exist as a going concern. It was taken over by Waterford a few years back. You may recall that on the national news a couple of years ago it was announced that there were to be a few hundred glassworkers made redundant - sadly, that was Stuart & Sons.
Waterford finally took the decision to close them down and took the name and the design catalogues/ledgers and other documents back to Ireland. Recently, I noted that the Jasper Conran range, which was originally instigated, and marketed by, the Stuart firm at around the same time as the Luxton Collection, is now apparently being given the Waterford etched mark on the base.
I was lucky enough to have a long conversation (2hrs+) with John Luxton at the Red House when there was an open day. He was there with one of the large Stuart & Sons design ledgers ( about the size of a broad sheet newspaper) and I took the opportunity to go through it with him. It was dated from the 1960's and continued into the 1970's. John showed me the drawing of the design that was used to introduce the Prism range. From this one design he produced the whole of the new range and oversaw its introduction. I would therefore venture to suggest that the original design dates from the 1960's and not the 50's, from what I saw in, and on, the ledger.
By the by, Waterford own Rosenthal as well.
Kind regards, Nigel