I find the P4 pretty hit and miss. One bus I've rode on was the same type of bus that is also used on the 356 which is a lower frequency bus route, so you can imagine if you get the single door buses, they fill up much quicker.

Does anyone remember when the P4 went along Lordship Lane and Court Lane in Dulwich instead of the Common and College Road? It was better in those days, but then Southwark Council put speed humps on the road which led to the re-routing along those busier roads.