Hi,
i'm near Cambridge and faced a similar dilema when it came to servicing as I had heard mixed opinions about Marshall Cambridge.
I took my LCR to Jabbasport near Peterborough in the end. They were £100 cheaper on a 20k service that Marshall and the level of service was excellent. They charged me exactely what they said they would and gave my wife a courtesy car at short notice. I will be going back for my 30k service in a few months. They really knew their stuff and took good car of my car so that wins my vote.