Originally Posted by terenz
That's because the U.S. and U.K. versions of both sites use different fare engines. The U.S. sites of both use one and the U.K. ones use another. And that's why the U.S. sites usually price the same as AA.com (or at least used to). I think the U.K. sites may restrict you from pricing the lowest available fare/fare bucket (BA saved these for connecting flights through LHR) while this would be illegal in the U.S. (according to an answer I received for a similar question/observation 2-3 years ago).
thanks. Expedia.com won't let me get past the pricing page -keeps rejecting and sending me back to expedia.co.uk (cookies?) where I can only get the higher fare. I'm already registered on travelocity.com from when I lived outside of UK so that should work ok. Presumably there is nothing to stop me using the US site and being billed in US$? Wonder if a UK billing address will affect this.