Hi,

Just a quick update on what actually happened ! BA was willing
to change my LHR-BOS flight for 200 Euros, getting me 5 hours
earlier to BOS. I did not take this option. They did allow me to
get on to the earlier AMS-LHR flight at no charge. I then used
the longer connection time to enjoy Galleries First at LHR. I was
OK with that :-) So..BA did show some flexibility there...

F.A.