I use Doncaster and Humberside for service quite a lot and they have always been very helpful and easy to talk to.
On one occasion when in a rented PA28 (outside class D), I had a 'non transponding' transponder (if you know what I mean). I had asked Doncaster and Humberside (my route meant that I changed from one to the other) a couple of times after recycling if they were receiving my squawk, both replied 'negative'. A new guy came on shift at Humberside and when I asked for a third time he stated that he hadn't seen a squawk from the aircraft I was flying for quite a few days. When I landed, I checked the tech log and found I had missed the comment that the transponder was US.
You can't beat a charming personalised local service like that!
I do think that the class D has a slight psychological negative affect though, which is probably down to my lack of experience.