Beware the RAF's secret and most deadly weapon: A sign that reads "Follow Me"!
I recently went to the Olympics Airspace briefing at the Royal Geographical Society, where there was actually a talk by both a Typhoon pilot and a Puma pilot with regards to interception procedures should you find yourself under a scrutinising eye. The key point that I took away from the talk was that should one inadvertently stray into restricted airspace, get on the radio to Atlas control (conveniently on the same frequency as Farnborough), apologise and turn away from London.
Any intercepting aircraft will be on the Atlas control frequency, so assuming the radio's working one can probably avoid being shot down in a ball of flames.