Hi adrums,
I owned a chauffeur company several years ago and I had 17 cars including 3 Rolls Royces.Mine was the largest firm in the south east. Many of our commercial customers were ordinary businessmen and women travelling to and from airports and various meetings. There was nothing special about them. Many companies like to impress their clients - and especially their visitors - by providing a chauffeur car for them in that manner. The journeys are always charged to the company account - and those of course are then written off by the accountants to the taxman!
It sounds as if the person you saw was a businessman being chauffeured in that manner. The journey wouldn't have cost him anything - nor his company at the end of the day. The plate is unremarkable as there are many private plate firms about. You just choose your plate from a list and pay them to transfer it. The taxman ends up paying the bill! I hope you appreciated paying your tax when you drove past him!
Don't be fooled into being impressed by Rolls-Royces either. They are horrible cars to drive and need to be constantly mastered (remember how Leslie Crowther lost control when he was tired). They are very cramped inside (most are only 4-seaters) and almost impossible to do any work on. All parts are outrageously expensive and your 100k estimate is way out as most new Rolls Royces top �300,000 now. However, unless they are bought by some fool whose just won the lottery, it's the taxman who ultimately buys and runs the car! Everything is written off by accountants as ''company expenses' - even the petrol.