This section starts by leaving NCR 4 beside the River Thames and following the Waterlink Way south through South-East London, generally on well-surfaced bridleways and residential roads and climbing gently. On leaving Greater London the route quickly becomes more rugged, following a number of paths and roads, including the long access road to Woldingham School. After passing under the M25 motorway the track quality improves again and the route heads west to Redhill, before again heading south, close by the London-Brighton railway. It passes directly underneath the South Terminal of Gatwick Airport, weaves through the runway approach lights and continues south to Crawley.
Between Redhill and Crawley the route duplicates Route 20.
This section is largely on well-made railway paths through attractive countryside and consists of the Worth Way immediately followed by the Forest Way. It finishes just south of Groombridge, with a short signposted spur to the village itself.
The first half of this section is on undulating country roads, passing by Eridge Station. About one mile before Eridge Station is a spur connecting Crowborough with the route. After Mayfield there is a steep off-road section. The route then follows the whole length of the Cuckoo Trail from Heathfield to Eastbourne, crossing NCR 2 at Polegate.