How CAMRA defines local varies from branch to branch to suit local perceptions. What a city dweller considers "Local" can be very different to a rural resident.
Most CAMRA branches define LocAle by the shortest driving distance from brewery to pub. For Trafford & Hulme branch we looked at whether to define "local" based on shortest driving distance or "as the crow flies" radius. What we found was that in a relatively urban area, 20 miles radius roughly equates to 25 miles driving, but that in an area with so many motorways, the shortest driving distance was not necessary the "greenest".
We therefore decided to adopt a 20 miles "as the crow flies" definition. For administrative simplicity, this is measured from the centre of the branch area - near the Bulls Head pub in Sale.
However, we're not going to be dogmatic about it. If there is a brewery not on our list but that is within 25 miles driving of your pub, we'll happily accept this as LocAle. Just contact locale (at) thcamra.org.uk & we can check the distance.