Richard - with respect mate, in the matter of language the fact that a usage is common absolutely DOES make it correct. It is in fact the only criteria which matters.

Academics and lawyers make specialised definitions which they use only amongst themselves within their own spheres of influence. These have currency outside those areas, but no guarantee of permanency.

Language shifts, adapts, reverses, augments, erronialises (see, you can even make words up -c/f Lewis Carroll), contradicts and generally tumbles and eddies in beautiful confusion down the centuries.

English has done more somersaults then most - and is one of the most expressive and powerful tongues in existence as a result.   

Lexicographers merely do their best to keep up.

There is actually no such thing as correct language. Only better or worse understanding.

Pip - feel free old chap. Everyone else does!

Tom