I saw this large wasp on heather next to a loch in Scotland, it had a hairy body ad very large eyes, it made a very loud deep buzzing noise as it flew off.
Not a wasp, but a horse fly, http://blashfordlakes.files.wordpress.com/2012/06/tabanus-bromius.jpg
Thanks, knowing now that its a Horse Fly I looked at some species and think Tabanus sudeticus looks a good match, this species occurs in Scotland. Bit disturbing to think this is a bloodsucker, it was huge! Maybe 30mm long body length, though recalling being bitten by much smaller horseflies elsewhere they seem to bite without being noticed. Never heard an insect before with such a powerful sounding buzz as it flies.
Oh, you'd notice this one if it bit you, all right. I got thrown by a horse that got bitten by one of these. Ouch!