"0" was the trunk line prefix, as I recall
All it did was tell the exchange that the subsequent string of digits should be routed externally.

So yes, the actual area code doesn't have an initial nought, but omitting the initial nought means that things don't work. It might not be part of the area code in fact, but it is in practice.

However, Galactic Yeti's point about 0207 and 0208 falls down if he tries to place an intra-London telephone call without the initial 7 or 8.
( flake has nothing against your right leg, Fri 1 Apr 2011, 2:27, Reply)