You probably received an email about this promotion directly from British Airways but if you didn’t, here is a quick summary.
BA is offering double Avios (that is double base points, ignoring status bonuses) until July 15th on a number of long-haul routes.
Here is a summary of the rules:
You need to be flying in Club World or First (or their American Airlines equivalents)
You must have a flexible or semi-flexible ticket (ie not a non-refundable I-class / R-class in Club World)
You need to travel by July 15th
You need to register in advance of your flight at this website
The most interesting part of this promotion is that in includes the American Airlines-operated routes from Manchester to New York and Manchester to Chicago.
Full terms and conditions, and most importantly the list of participating routes, can be found at the website link above.