Thanks Gents.
Clearly eitheer my fuel gague is iffy or I an trusting the modern pump to knock off when full.
If it is the fuel gague it sounds like testing that out whilst 1,000 miles away from home would be foolish, so I think I will go with filling her up as much as possible and see if I get a better range.
I am getting a range of about 220 miles to the 1/4 fill point, which isn't too bad. I am guessing it is around 22 mpg, but I dont have the figures with me at the moment as they are all in the car.
Regards
Mark.