Our group owned C172M is based at Biggin Hill in hangar 504 next to Mr Singh's maintenance hangar. I have been flying out of here for about 2-3 years on and off. We share the hangar with a couple of multi-engined aircraft, several SEPs and two Varieze aircraft. I have been talking to one of the pilot/owner over the winter and he seems very happy with the airfield and the services provided.
My experience of the services there has always been that they are professional and very helpful. When asking for a departure to the North through the LCY they ring Thames Radar and check for me what the chances are when I am at the hold and advise accordingly without me having to request this. I have visited the TWR on several occasions to discuss issues with the controllers or generally say hello when they are not too busy and have learned a great deal from them.
I hope that Biggin Hill don't get the idea to push out SEPs in favour of jets that would be a disaster for our group.
Another alternative would be Redhill (EGKR). Our group use this as a base in the summer season and it is a nice airfield. They have a good website
here which Fraser, the Deputy SATCO, has done some good work on so I will give them a plug!