Perhaps Wilde had been to the Colonial and Indian Exhibition in London in 1886?

(Incidentally, Ackroyd should not have been given credit for locating that Berlioz quote - he uses research assistants to do all the difficult stuff).

That short passage suggests strongly that Wilde had seen what he describes. I can't imagine Tunisian oud players ever trying to make a living among the London street musicians Berlioz saw, or anybody charming cobras in public without coming to the attention of the police. The occasion must have been of a different kind.

It's a really neat puzzle.