I thought it was still, if not illegal then at least discouraged by the HC to overtake an indicating bus? One time in Walthamstow I saw a crappy little Corsa do exactly that, the bus scraped the side of his car and watching coppers immediately said the car driver was in the wrong.
Just silly. It used to be that you were legally obliged to let buses out when indicationg, but that rule (inexplicably, to me) was changed*.
*possibly bollocks