Yes, we've been and we still like it there although its now run by the Ayotollah. Walking distance to little village square, two pubs (Three Jolly Butchers is far superior), bacon butties in the square at weekends, little village shop, beautiful church etc. Not far from St. Ives. Nice walks along river, Mill is quaint and attracts canoeists, thatched cottages in vicinity etc. Showers and toilets very nice. The site is quite open to the public though as the mill is Natural Trust but we have never heard of anyone having any problems. Can be a bit noisy if pitched alongside the tenters who tend to be groups who sit outside till the small hours.
It was one of the first places we ever went and we've been quite a few times. Location is great for what we want and even though the warden has been rude on occasions we put up with her. However, I did see a van pull on and off again on our last visit due to the way the warden spoke to the couple who were intending to complain about their treatment. It seems to be an ongoing problem but she is still there......
Don't know where Bassingbourn barracks is so don't know whether it is near it or not.