Thanks for that Roland and I for one will check it out when in London next time.
I know exactly where you mean and this now appears to be the preferred spot for most of the street entertainers in Covent Garden now, rather than in the main square or piazza itself.
From my observations there seems to have been lots of guitar and bongo bands of late and a few juglers. The magicians have seemed to be in short supply which is a real shame.
Perhaps we should all travel there, meet and perfrom a mass magic show

Member of the Magic Circle & The 2009 British Isles Close-Up Magician of the Year
It's not really an optical illusion - it just looks like one!