Ulmus × diversifolia, also known as the Diverse Leaved Elm, he recorded its distribution in which county town of Hertfordshire, England, and is also a civil parish in the East Hertfordshire district of the county?
Ulmus × diversifolia:  He recorded its distribution in Hertfordshire, between Hatfield, Hertford and Watton-at-Stone, and in Suffolk, where it was common along the coastal plain from Ipswich and Felixstowe to Lowestoft and Beccles, occurring inland as far as Diss and Debenham, and probably extending further north into Norfolk and south towards Colchester, Essex. Hertford: Hertford (/ˈhɑːfəd/, /ˈhɑːtfəd/) is the county town of Hertfordshire, England, and is also a civil parish in the East Hertfordshire district of the county.
Hertford