fifteen f**king pound indeed.
Anyhow, Oak green, was a rare option on the mk2's, it was an understated colour, and indeed made the golfs look cool and classy, it does have a slight reference to racing green (they share some of the same paint colours), but nothing more.
They are more popular now as finding one in good condition is becoming hard. As with anything the harder it is to come by a car then the higher the price will climb. So there you have it.