I hope folk won't mind me sharing this, as it's not BA/Oneworld, but Singapore Airlines are currently offering fares for as little as £250 return from MAN to IAH direct (I've heard rumours of £199 return but not seen them). Fare is KT5GBR - not sure if anyone could post the rules/validity?

This is in economy on SQ51/52, an A350, and it has stuck around for several days - I've never flown SQ but have heard good things about its economy class. Can anyone confirm if that applies on the A350? The very cheapest BA/AA is double or more and involves a change at PHL or LHR.

An example is below, it is pretty easy to find via Google Flights or Matrix, and clicks through to the Singapore website reliably.

Hope it is helpful for somebody!