Tis only worth what someone is willing to pay, and depending on how it has been stored, that fact it's only done 300 miles shouldn't put people off.
There was a couple of months ago on Ebay, a 1982 Mk5 Cortina, unregistered with only 82 miles on the clock!!!! been in a Ford showroom all it's life, and it made £8k, do you think the new owner would have been worried about that?