thanks Ian, I was quite lucky with that location and it was easy parking, worst part was that I had to drive past Duxford to get home and they were holding the A505 traffic to let the show traffic out
As for my location, if you look at the ordnance survey map at Thriplow, about a mile north west of the airfield there's a road (Church Street) that that runs round the south east side of the village and at the south east corner there's a footpath that goes south east round a farm down to the A505, I parked in Church Street - very wide grass verges and loads of room, only about 8 cars when I returned, and walked down the footpath to about 150 metres from the A505 where another footpath goes east, I was on the track there. I might have been a bit better another 100m or so further back because of the high trees but they did create some hedge hopping impressions on some photos. It was pretty good although it was about 3pm or a bit later before the sun came round to light the aircraft, I'd certainly consider going there again although if I could find a similar place just east of the M11 and north of the A505 that would probably be a bit better especially for the aircraft banking and turning in towards the airfield.
HTH
Andy