A few years back (yes this is another gliding story!) I was climbing in a nice thermal near Boscomb Down Empire Test Pilot School, and inadvertently invaded their airspace. It does get your attention when a couple of fast military jets appear on either side of the glider! They quite enjoyed my reaction, getting the chance to chase an intruder made their day! I only wish I had been switched on enough to snap a photo with my turning point camera.
Didn't get round the 300k attempt that day, but did get back to Booker without landing out.