It's a bit like a sort of bigger TARDIS isn't it? Like Dr. Who decided to move into something larger but still unobtrusive....
They do exist then! I've always liked the Wills kit, (and the rest of the range) but have never found a use for one, or seen one on a layout.
There are quite a few dotted about and most are still in use. This one is just up from Harrods and we passed another surrounded by cabbies drinking tea near Eaton Square.
It has occured to me that this is what arrives when Dr Who asks for reinforcements.