Once when flying over Beaulieu disused airfield circa 1,000ft I spotted a large RC model aircraft off my startboard side level with me. I thought they are restricted to 400ft. Hit one of those and they could cause some damage.
I flew into Elvington a couple of weeks ago where they regularly fly those big jet powered r/c models. When you gett PPR the modellers are supposed to be told when you are coming in and leave a gap. There had obviously been a communication breakdown as one zoom climbed just past my nose at about 150mph, and they are big things. Not impressed.