That particular seller seems to concentrate on clean, original cars with plenty of history.
These are exactly the sort of cars that collectors will increasingly be on the lookout for as Mk2s move more firmly into proper classic car territory. Like it or not, the amount of modified cars out there only helps drive up the value of original cars, as that's precisely what classic car enthusiasts look for above anything else.
£4,750 does seem a bit steep though for a car without matching engine and chassis nos.