Thanks for the informative and useful thread.
After reading the thread and browsing the High Street, I found the
Oakley Crosshair is quite excellent:
- huge unobstructed field of view
- arms with kinks to lie flat against the head, so comfortable underneath a headset
- usual Oakley optical quality and frame quality
I have a mild prescription - "spectacles advisable but not mandatory", it says on my Class 2 visual examination report. I got them with the plain grey (18% transmission) lens, and I'm very impressed. Good value at £240, too. I think they're about £140 without prescription lenses.