Mark James Boyd wrote:

Have there been any actual airplane-glider midairs in the UK
that weren't takeoff/landing related (within 4 miles of the airport)?

I don't know for the UK, but there was one in France in 1999.

http://www.bea-fr.org/docspa/1999/f-...f-xb990212.pdf

Miraculously nobody was injured, but the result is that another piece of
airspace has been changed from class E to class D.

Stefan