Re Sweet Chestnut in Yorkshire Smojo, to quote from Scotty in Star Trek, "Ye canna defy the laws of physics!"
I suspect you're beyond the range of climate that SwC. will happily tolerate. Reality is it doesnt fruit well even in Southern England where its more common, better on the continent. In Yorkshire, it'll struggle. According to the following detailed SwC report, there are less than 50 hectares (nout) of SwC in Yorkshire. I think it get chewed by the Polar Bears. Surprising the difference that 3 or 4 degrees Centigrade makes to the flora, but if you drive from the South to North in a day in late winter / early spring, you do see a real visible change in the trees and general abundance of greenery. Bobby Robson once noted in frustration about the Newcastle United pitch, "grass can't grow up here !"
http://www.swog.org.uk/wp-content/uploads/2009/03/627.pdf