Length: 12½ km (7.8 miles). Toughness: 3/10
10:25 Hastings service from Charing Cross (Waterloo East 10:28, London Bridge 10:34, Orpington 10:50, Sevenoaks 11:00), changing at Tonbridge (arr 11:08, dep 11:26) for the Redhill train, arriving Penshurst at 11:34.
Alternatively you can travel out via East Croydon, eg. on the Thameslink service (St Pancras 10:10, London Bridge 10:25, East Croydon 10:42, etc), changing at Redhill (arr 11:00, dep 11:09; don't dawdle as you need to change platforms) for the Tonbridge train which gets to Penshurst at 11:31. Cross the footbridge and wait a few minutes for the train from the other direction.
If you have any "Any Permitted" route ticket you can travel back from Penshurst on the hourly trains in either direction, although both services leave at about the same time: eastbound via Tonbridge at xx:31 and westbound via Redhill at xx:34. If you travel out on a cheaper "via Redhill" ticket you'll need to return the same way.
This is one of the shorter variations of a group of walks around the attractive Kent villages of Chiddingstone and Penshurst, although this one only visits the former. The suggested lunch stop is the rural Rock Inn at Hoath Corner, but if this can't oblige it's not much further to the Castle Inn ("open for light lunches and drinks") in Chiddingstone. The village also has the Tulip Tree tearoom and another in Chiddingstone Castle, while the Little Brown Jug provides a useful watering-hole if you have to wait for a train at Penshurst station.
You'll need to bring the directions from the L=swc.92.c page. To reduce the amount of paper printed, you can click on Option c (or "Alt." in the heading to include directions for all the walk options starting from Penshurst, which would allow you to switch to a longer ending via Penshurst village to Leigh station).