I don't want to be the harbinger of doom here but CAP suggests that the trade price for one of these, now is in the £1,300 range

- that'll be for an average condition trade-in.
Yours looks to be much, much better than that, well cared for and unmolested... so I would have thought a ceiling of closer to £2,500-£2750 would be closer to the mark. At that price its a lot of car for the money but may indicate why you have had limited interest at £1,000 more...
As suggested, you might be better off keeping it because I'm sure, from what you have said, it is worth more to you than that...
I have a soft spot for these I remember test driving one years ago with a view to having one as a company car but for some reason - the company didn't like the idea... So ended up with a Fiat Coupe 20v...