I am begining to think it was something simple like a Hawk.
The sound, speed and manouverability would match a Hawk. Tried to get digital pic on my zoom camera, was able to track it but camera took a long time to focus and locked on out of focus.
I have 9000 hrs flying and have seen close up Tornados, Hawks, etc, and can usually quickly recognise what i have just had a near miss with! But this a/c still bit of a mystery.
Thats what prompted me to put forward question.
Just looked at pics of Mirage 2000, could be match.