Oh..confusion rules...

well..just checked on Autotrader:

1986 Rolls Royce Silver Spirit in white is £5,500.
Same car in metallic green with 168k miles is £6,495
1985 Brown 4dr auto: £7,000
1985 White Silver Spirit with 60k miles is £8,950.
Light-ocean blue C plate with 70k miles is £9,995
Deep-ocean blue similar miles, same price
D plate Silver Spirit Mulsanne Auto in Royal blue, 69k miles: £11,995.

Similar prices but higher mileage doesn't seem to be much of an issue on the rollers prices.
The £5,500 was the cheapest 1986 car btw....but the newest Rolls are around the £200,000 mark: much higher than the original S1 values.