We are making more of this than I intended!

If you have a play called 'Timor of Athens' it is reasonable to assume Greece will feature heavily. If you have a play called 'Two Gentlemen of Verona'you would expect Verona to have some significance. So if it is "The war of the Worlds" it is reasonable the world will stretch a few miles beyond Woking.

I would counter the suggestion that it is reasonable to assume it is local by saying it is more reasonable to assume it is not. And the world did have a fairly good communication system. Telegraph, railways, national papers. And rumour has always spread well.