If I was in your shoes:
Keep it. I can't imagine it is worth anything as an investment. Its a financial burden in terms of depreciation, insurance, VED, MOT, service. But you'll be driving along a road one day, and regret not having the R32 to drive.
If I was advising you:
Think of how much fun you can have with £8,000, and then how much fun you are having with your car now. 500 miles a year isn't great for the car or the engine, and a lot will depreciate through time rather than mileage. You are not generating a low-mileage classic, you are not justifying ownership.
Other options:
1) Car share. Joint own it.
2) Sell and hire something silly every so often.