The B238 is a short B-road in southeast London. The road was unclassified in 1922 but appears to have gained its number in the mid-1920s.
The road starts on the western side of Peckham Rye Common where the southbound B219 TOTSOs southwestward to the right, while we take the left-hand, southeastward fork, continuing along the edge of the common as it becomes Peckham Rye Park. Soon after passing the modern buildings of Harris Boys' Academy on the right there's a short stretch of shops and from here the road becomes wholly residential for the first time.
We continue along Forest Hill Road, passing Camberwell Old Cemetery, after which there is a brief, and unexpected, D2 section. We climb to a sharp left-hand bend by St Francesca Cabrina school and continue east along Honor Oak Park. After passing One Tree Hill (a park) we cross the East London Line via two adjacent bridges (making the road briefly D2 again); the eastbound bridge is the original and has Honor Oak Park station alongside. The road continues a short distance further to end at traffic lights on the B218. Some maps continue the B238 on the far side, giving it a short one-way loop onto Brockley Rise, approaching the B218 from the other direction slightly further south. This junction appears to be a roundabout but traffic on the island has to give way to through traffic on the B218.