Peak to Peak from Clingman's Dome to Waterrock Knob via the MST. 

The Waterton Triple Crown is completion of the 3 best and most stunning trails in Waterton Lakes National Park:  Akamina Ridge Trail, Carthew-Alderson Trail, and the Crypt Lake Trail.  The local challenge known as the Waterton Triple Crown has been in place since at least 2011 and encourages hikers to complete the 3 hikes within 1 hiking season:

https://www.watertonpark.com/activities/triplecrown.htm 

Circular route primarily through Buckinghamshire and Oxfordshire on tracks and trail, with small amounts of road.

https://ldwa.org.uk/ldp/members/show_path.php?path_name=Jubilee+Way+%28Bernwood%29