The A2215 links the A202 Peckham High Street with the A2214 at Peckham Rye.
The above is certain; however, the actual route is debatable as different maps (even different scales of the same map) show different routes, most roads in the area are one-way and road signage is minimal.
In 1922, the A2215 ran along Rye Lane and then the western branch of Peckham Rye. However, the northern end of Rye Lane is now pedestrianised, so the road has been rerouted and now starts by going south along Clayton Road to the east.
According to some maps, the remainder of Rye Lane is still the A2215, with Hanover Park being the link between the two. Other maps (like the one on the right) suggest that only that part of Rye Lane directly north of Peckham Rye is still the A2215, with Copeland Road (northbound) and Consort Road and Heaton Road (southbound) the way through instead.
It's probably better to be a local and know the roads well enough not to need the numbers. The number doesn't appear on any signs anyway.