I've been on this more than once, but also had the privilege of seeing it multiple times - both from the local roads and from the air - since I co-owned a flight school at Lydd Airport during the '90s. Lots of history in this area. "Sound Mirrors" from WW1 then also the Royal Military Canal, built for defense not navigation. Very close to Rye, Folkestone and Dover, not too far from the Battle of Hastings!