It's rare, alright.
There were 240-odd Series 1, 200 or so Long Noses and about a dozen Spyders (GTS). The youngest of those cars is forty years old this year. Values for excellent cars range from £100,000 for a spyder to £200,000 for an alloy-bodied S1.
Having said which, if all the cars currently in existence have the books already, then it isn't too rare anyway.
It'll sell to an automobilia collector, rather than a genuine owner.
PJ