I can see it making upwards of £100k. Not so much because it's worth that alone, but there are always people out there that will make a statement purchase when it's for charity. Just look at the sort of money people pay for a day weekend driving Chris Evan's cars.
I'm sure whatever it sells for will be loose change to the winning bidder who will just buy it because they can. What a lovely car to have sat in your garage tho'.