The Round Aylesbury Walk (TRAW) is a 12- 13 mile named trail that circumnavigates Aylesbury Town Parish. The route is waymarked and maintained by The Aylesbury Ramblers Group and it is easy to follow.
Note that this is the shortest of 3 Alyesbury "ring" walks:
https://fastestknowntime.com/route/outer-aylesbury-ring-uk, 85 km
The Stour Valley Way is a long-distance footpath in southern England. From the source of the river at Stourhead, Wiltshire, the path travels southeast through Wiltshire & Dorset to Hengistbury Head near Christchurch. The path uses public rights of way and permitted paths to follow the course of the River Stour, as well as taking in a few extra Glorious Dorset beauty spots along the way: Hambledon Hill and Hod Hill. Majority of the route is rural and scenic, plenty of public houses en-route and a couple of shops but limited opening hours.