Yes, apparently it's true, if Jensen Button doesn't win at San Marino, he may be imprisoned in the Tower of London by order of Her Majesty!
THE GRAVEL TRAP - Jenson's Royal Order (ITV-F1.com)
I'm guessing he won't actually be imprisoned, but if the Queen really has given him a royal commandment to win the race then I'm guessing there is still old laws in place that say disobeying a direct order from the ruling Monarch is punishable by imprisonment
On a related side not - do you think that the Queen ever watches the F1 and goes "one did not enjoy that race since one's damned corgi's were yapping throughout and one's remote control was elsewhere so one could not turn up the volume enough"?