It is an inescapable fact that many a late Georgian or early Victorian music cabinet must have contained at least one set of piano variations on an operatic theme by Rossini. There are just so many of them! Since they proliferated in the 1820s (ie the last decade of Rossini’s operatic compositional phase, and the era when he also visited Britain), you won’t find them listed in Kassler’s Music Entries at Stationers’ Hall – his bibliography ends in December 1818. But you have only to search Copac or glance at St Andrews University Library’s listings, to see how many composers were inspired to write virtuosic variations on the great man’s tunes.
What did Rossini think of this, I wonder? I’ve only started to scratch the surface of this particular enquiry, but to date I’ve discovered only that copyright legislation was not as advanced in Italy as it is in the UK. What’s more, there may not be very many extant letters by the great man from the 1820s, and that the authoritative modern edition of his letters is in Italian. I do know Rossini would have been very conversant with legal documents, considering the number of contracts he signed for his many, many operas. None of this tells me (yet!) what Rossini thought of other composers making free use of his lovely melodies.
What I do have is William Lockhart’s article in Music and Letters (vol.93 no.2, 2012), ‘Trial by ear: legal attitudes to keyboard arrangement in nineteenth-century Britain’; Charles Michael Carroll’s ‘Musical Borrowing – Grand Larceny or Great Art?’ in College Music Symposium (vol.18 no.1, 1978); and Derek Miller’s Copyright and the Value of Performance, 1770-1911 (2018). I shall in due course have a couple more books on Rossini, so I haven’t yet given up on finding out how he felt about this evidence of his popularity. Maybe he just felt flattered – but I’d love to find his own words on the subject!
As for his published letters? Well, I may have to look for them. I know a little Italian, thankfully. But meanwhile, if you know anyone who has read the recent edition, please do let me now! I’d be deeply grateful!
During the reign of King George IV, Johann Peter Pixis wrote his Hommage a Clementi, a set of piano variations on ‘God Save the King’, op.101. Published in 1828 by S. Chappell, and also distributed by Henry Lemoine, copies went to all the copyright libraries. As I’m transcribing each item on the two Advocates’ Library music lists, I’m looking to see where copies survived, and it’s rare to trace such near-complete coverage as I did with this piece. Playing my game of ‘Happy Families’ with the list dated March 8th, 1830, I checked off an almost complete set still extant, in Aberdeen, St Andrews, Glasgow, Oxford, Cambridge and the British Library. Clearly, variations on ‘God Save the King’ were generally considered worth keeping. Indeed, St Andrews and Cambridge each hold two copies. The popularity of the tune is corroborated in a recent book, 
Karen McAulay, Musicologist 