The A204 is a short road in south London. It is perhaps surprising that it was not numbered as a continuation of the A203.
The route starts as a one-way left fork from the A23 near Brixton Town Hall. This is Effra Road, named after one of the "lost" rivers of London. Formerly the A23 and the A204 southbound were multiplexed on this short section, but in recent years the A23 has reverted to two-way operation at the start of Brixton Hill and the A204 sets off on its own. At St Matthews Road the northbound side has to turn left to avoid the one-way street and this is where the the A23 formerly departed.
The A204 climbs a hill with intermittent bus lanes on both sides to the junction with the A2214, which has a traffic signal. It continues climbing, but is now named as Tulse Hill, to reach another traffic light at the junction with Upper Tulse Hill/Trinity Rise. This section now has humps. It descends gently to the one-way system at Tulse Hill itself, where it meets the A205 South Circular Road and the A215 Norwood Road and terminates. The entrance to the one-way system is free-flow.
One final point of slight interest: Abbess Close is on the right just before the one-way system starts. What is special about Abbess Close? It is the first entry in the index of the London A to Z, and therefore the one used in the illustrative example of how the index works.