Have you listed it without reserve ?
Had you listed it with one it would have been quite interesting to see what Ebay buyers made of it - the problems arise with shipping, people claiming it has arrived damaged etc
You should e-mail Philip Serrell and see what he thinks - he's not too far from Brighton. Sworders and Woolley & Wallis would be my other choices near you - high quality catalogue auctions with internet bidding and well publicised in the Antiques Trade Gazette
The £350 early " bid " is encouraging but also implies it would fetch more.
The pic from above you've used on Ebay really shows the quality.