Personally, I would expect the valuation to be in the region of around £13-14k but I will make contact with a few of the recommended and see where we go.
Jamie, first of all, sorry for your loss.
Used Morgan values go very much on vehicle condition. For that you are right in asking a dealer or Morgan specialist to give a valuation - on a sale basis (what they would buy the car for).
To be honest I will probably keep the Morgan in my Dads honour and use it regularly.
Should that happen I will just say: welcome the world of Morgan motoring
Good luck with sorting probate.