Are you sure? The old 'British Billion' was 10^12, but even that is rarely used any more. I've never seen an 'M' suffix used to mean anything other than 10^6.

I don't think that's right. 10^6 is a million in both languages.

10^9 used to be a milliard in British English but is no longer used. It is now referred to as a billion.

10^12 used to be a billion in British English but is now referred to as a trillion.

Edit: http://www.youtube.com/watch?v=C-52AI_ojyQ explains it all quite nicely.