I have found four large DNA families (third is pending)

1. The major grouping (so called "superfamily") shows six branches with a common ancestry.This group (and after deep-clade (SNP) testing) falls within the U198 project with Family Tree DNA and also known as S29 with another leading testing company.  These men, all of English origin, who are U198, come from Rye, Sussex(Mariners); Canterbury, Kent(Gamekeepers); Hertfordshire (Blacksmith/table-makers family); London and (possibly) Cambridge (The Thames Watermen and The Papermakers); Essex CURDS; Buxted, Sussex (Gardeners).  
I'm still looking for new members from Derby/Durham and Dartford who I think will be the London branch.

2. Maidstone (Wateringbury/Yalding) Family.

3. Tonbridge (Brenchley/Pembury) Family (pending being tested). 

4. The Americans (Virginia/Kentucky) early settlers and their plantation staff, who adopted the Curd surname. Of those who tested one came from Ireland

Discovery; U198 CURD mariners from Rye, Sussex is the same branch YDNA at 37 markers as surname "Medhurst" differing only when testing for 64 markers. So their Curd surname may have been adopted