A question: does the Royal Ballet really perform the Petipa/Ivanov choreography? They might use more of it than other companies, but I was under the impression that their production had been altered by Ashton, among others. They also don't seem to have enough dancers to perform it, as it requires a very large corps de ballet.
I'm afraid this is slightly too rose-coloured, Hans. The Russians dropped almost all the mime in the great classics in the Soviet era and we cannot properly speak of a tradition of mime anymore, as for instance the Danish School/Ballet has. We could see how awkward they all looked when they were asked to mime in Vikharev's productions of Petipa's "Sleeping Beauty" and "La Bayadère".
The Royal Ballet production of Swan Lake is one of their 5 ballets based on the notes from Nikolay Sergeyev, so the text is supposedly quite pure; but it's also clear that he had to adapt his Imperial Russian Ballet productions to suit the new English location - scale, numbers, means.