Have a large maze made like the ones that you see rats being tested in on science programmes and such like.
Make the maze about 3m square, and about 150mm high, sat on a table 3m square, the table should have simple 25mm steel box section legs and be sprayed white to match the maze.
Buy a kitschy china ornament of the Queen, around 250mm high, I’m sure there’ll be plenty to choose from in every charity shop in the UK before the years out.
Place it in the middle of the maze – “The Queen is now leaving the royal box”.