Not a sighting or UFO, but what, for me, was a strange experience.

This was 2007 during a visit to Boleigh Fogou in Cornwall. In my blog of the time I described it thus:

"I had a weird experience here. After we had explored the dank and rather muddy interior for a while, Sue and Will went out to find the other entrance, which was blocked off from the inside by a wooden barrier. Matthew climbed out, and he nipped ahead to find them. I stayed awhile to get a feel for the place. It has an interesting little creep, with a narrow entrance. The creep winds around to the left, almost going back on itself. Once I had seen all I wanted, I climbed out too. Matthew had been waiting, but darted ahead of me through the bushes. I followed, but within two seconds realised that I was lost! I couldn't work out which direction the others had gone, or even which direction I had come from! This is particularly odd for me, as I usually have an unerring sense of direction. I called out, and soon found the others, but could not shake the sensation of disorientation until some time after we had driven away to head onwards for the Merry Maidens stone circle."

This might not sound like much, but it freaked me out at the time. When I posted a link to this from here, Rhiannon commented that it sounded like a visit from the pixies. As good an explanation as any! The strangeness of the feeling has stayed with me too.