So today my car was collected from my office and returned 4 hours later no more servicing message, bright and clean and no invoice!
It turns out that the system timings had not been reset from the day it left the factory (which suggests a build date for my car of April '07) rather than when it was registered and first driven (June '08). As such the clock had been ticking for more than a year when the car wasn't actually being used.
I received an excellent service from Berry's BMW in Chiswick, London, and never again will I go near Park Lane/Battersea BMW who were typically rapacious in their quote and generally unhelpful (and of course they did not offer to collect and deliver).
So all is well and good. Thanks for all of your help.