Now that you mention the subject, I hadn't even noticed that this Box didn't have an SJA badge back in the day either.
And yes, if it hadn't been for Tram, Bus and Train enthusiasts, I'm afraid we'd be up a creek without a paddle looking for Met Boxes.
Oh, and e TARDIS as a double-decker bus has been done with Iris Wildthyme, as I recall. Get both of them playing Routemaster and throw in The Knight Bus and things could get really interesting ;D.