Woodvale Post Office, Forest Hill

With the closure of Woodvale Post Office a few years ago, this painted sign turned into a proper ghost sign.

Forest Hill
Woodvale
Post Office

This was painted over an earlier sign. Only an ampersand below the final letter of "Woodvale" and the number 23 below "Office" can still be seen properly. Could this number have been part of a phone number, in which case it would have been preceded by the three letter code of the local exchange?

Location: Wood Vale / Pictures taken in August 2012