Re: Mini - not really
As someone born and brought up in Cambridge, I knew how this was done from only a few years later. I bet there must have been thousands who knew,
However, it was a brilliant plan, fairly well executed.
However, nothing beats the (much earlier) prank in which a bunch of gas board workers digging a hole in the road were told that students dressed as police were coming to harass them, and then the police were told a bunch of students dressed as gas board workers were digging up the road. Cue major fracas!