I used Jem in August for my 60,000 mile service, MOT and cam belt change. They also replaced the spark plugs, brake fluid, transmission oil, rear axle oil and recharged the aircon system. In all it came to just under £1000 which is a fair bit cheaper than Lexus dealers were quoting. They also give a 10% discount for LOC Gold members.
They supplied me with a Suzuki Swift courtesy car (they are now a Suzuki dealership) which I had for 2 days while they did the work. I cannot fault their workmanship either, the car is running fine so if your car needs servicing I would say try them, I don't think you'll be disappointed. :)
Use this link HERE to go to Jem's Lexus page for a quote