Has the creator of the Jacobite 'Amen' glasses been revealed?

At the international conference held in Edinburgh in October 2010 to celebrate 400 years of glassmaking in Scotland, two glass researchers came together in an endeavour to solve one of the mysteries of Jacobite glass made between 1743 and 1749.
The 'Amen' glasses are unique. Only 37 genuine glasses are known and they are some of the most valuable of 18th century drinking glasses. The historical sentiment encapsulated in these glasses is such that they sell for tens of thousands of pounds. They are engraved in diamond point with verses of the Jacobite anthem together with the cipher and crown of the old pretender, James, and the word Amen. The sentiments are explicitly treasonable, and in the 18th century, especially after Culloden, possession of such material was not without considerable risk. Consequently, some of the glasses are still protected and concealed in a velvet-lined mahogany box.
Ian McKenzie, a professional glass engraver working in Australia, has been studying the Amen engravings for some years. Geoffrey Seddon has also studied Jacobite glasses for over 30 years. In the 1970s, having photographed 16 Amen glasses in close-up detail, Seddon, with the help of a forensic handwriting analyst, was able to show that the Amen glasses are all the work of a single engraver. As described in his book, his study also revealed that four glasses were forgeries and that two of those were in important public collections.
Ian McKenzie came to the conclusion that the most likely engraver of the Amen glasses was a Scottish artist, the famous 18th century line engraver Sir Robert Strange. In the 18th century, line engraving of a polished copper plate was an extremely important art form, as it was the only means of illustrating a book or making a print of any kind. One of the tools used is a diamond point, and it was the expert use of this that eventually made Strange famous.
Seddon, in his lecture 'Rebellion and Scottish Glass', told a rapt conference audience how an analysis of the detailed photographs of the Amen glasses had revealed the profile of the engraver. Study of the improving quality of the engraving showed that most of the Amen glasses were engraved over the very short period of a couple of years. Strange's life (his marriage to an ardent Jacobite, Isabella Lumisden; his period of service in Prince Charles's army in the '45 rebellion; his life in Edinburgh and his period in France) fits the profile of the Amen glasses perfectly. This compelling circumstantial evidence is a strong indication that Strange was the engraver of these glasses. His arguments were so persuasive that one sceptic in the audience rose at the end of the lecture and told how he had come to damn the argument but was leaving a convert.
Amen glasses have always reached high prices. The Seddon-McKenzie revelations seem set to ensure their value will now increase still further.