Route map: https://www.outdooractive.com/
Castle Drogo official website: https://www.nationaltrust.org.uk/visit/devon/castle-drogo
Teign Gorge Classic Circuit National Trust info: https://www.nationaltrust.org.uk/visit/devon/castle-drogo/teign-gorge-classic-circuit
Walk alternative:
Castle Drogo and Dartmoor Way Walk (circular)
Similar route to the Teign Gorge Classic Circuit but route passes to the north of the River Teign (along the Fisherman’s Path) rather than to the south.
Route map: https://www.outdooractive.com/