Pauldb, This thread which you've previously posted to would suggest otherwise:

http://www.flyertalk.com/forum/briti...-open-jaw.html

There are claims by a FT member that they have achieved this, and the 241 appears to override the IATA requirements.

If when I come to book it doesn't work, then my back up plan will be the same (ish) route out and back. I'll just need to decide East or West