We are loosing our version to a fungus, from Holland.
Holland has wiped out a lot of our native trees, three are on the threatened list now.
Oak, Birch, Horse chestnut.
We may be importing yours some time in the future.
The horse chesnut trees I remember were HUGH and healthy.
http://www.arborday.org/GeneralInfo/SiteSearch.cfm?criteria=horse%20chesnut&q=horse%20chesnut
A place to start? I don’t know the export laws, but perhaps one tree can start something growing!
Dutch elm dz?