16 km (10 miles) or 22.7 km (14 miles) 7/10, maybe 5/10 for the 10 mile version
It's not as complicated as it sounds! (and has been tested). Most of the walk follows quieter trails than the main south downs route on other SWC walks, with fine views. It should work well clockwise with a Bishopstone start cutting out nearly two miles of seafront walking. The instructions are pretty sketchy so you really need a map or GPX to do this walk anyhow.
A 10 mile version is available if you end the walk at Eastbourne Road, Seaford (bus stop for 12A, 12X, 701 etc. to Seaford station and onward to Brighton, marked on the map here), or take the last chance for a longer Wednesday walk before the clocks go back, with a spectacular finish over Seaford Head.
Trains: 0954 from Victoria (Clapham Junction 1001 East Croydon 1010) changing at Lewes on to the 1100 arriving Bishopstone 1116. There is only a 4 minute connection time which normally involves a dash across the station – quickest if you are in the middle of the train from London. Returns from Seaford via Lewes at 24 and 53. If you book now (1 Oct) you can get advance tickets for £10.65 out and £4.65 back (with railcard).
Lunch and tea: numerous options in Alfriston and Seaford respectively, all set out on the Glynde to Seaford walk pages.
Short walk option: as well as the shorter starts and finishes proposed above, you could take a big short cut 3.6 km after Bishopstone which misses out Alfriston and reduces the walk length by a further 10 km.
For walk directions, map and GPX click here.
T=swc.314