There is a fantastic off road circular 10K around Steeple Morden on the 23rd September. The course goes through the old Steeple Morden Air Base, along the Icknield way and other country footpaths. All the money raised is for the local primary school. It is organised by one of the school staff who is also a member of Royston Runners.
Online entries are here https://www.steeple10k.co.uk/