Length: 15½ km (9.6 miles). Shorter afternoon options are available. Toughness: 3/10
10:04 Dover Priory service from Charing Cross (Waterloo East 10.07, London Bridge 10.13), changing at Tonbridge (arr 10:47, dep 11:01) for the Redhill train and arriving Penshurst at 11:09.
If you prefer to travel on the (less expensive) via Redhill ticket, the Thameslink Three Bridges service leaves London Bridge at 10.21 (Norwood Junction 10.32, East Croydon 10.36), changing Redhill (arr 10.52, dep 11.00) for the Tonbridge service to arrive at Penshurst 13 minutes after the others at 11.22
If you have any "Any Permitted" route ticket you can travel back from Penshurst on the hourly trains in either direction via Redhill at xx:09 and via Tonbridge at xx:22. If you've travelled out on a cheaper "via Redhill" ticket you'll need to return the same way.
This walk takes in the area around Bough Beech Reservoir, a large body of water tucked away in the Wealden countryside which is surprisingly well-hidden until you get close. The suggested lunch stop is in the hamlet of Bough Beech, which you should reach about 2hrs 15 mins into the walk. You'll need to book a table at the up-market Wheatsheaf if you want an indoor table for lunch. For a picnic, look out for a spot along the morning route, otherwise walkers have previously sat in a pleasant field behind the pub garden. From Bough Beech the main route follows the longer of the three possible afternoon routes via Chiddingstone and/or Penshurst village as well. Other, less familiar and shorter afternoon routes are available (see the clickable map on this walk's web page). All routes return to Penshurst station where the Little Brown Jug provides a pleasant place to wait for a homeward-bound train.
Be sure to download the latest version of the directions from the L=swc.300 page. If you're printing the directions and know which afternoon route you'll be taking, you can save paper by clicking that option.