Contrary to what is suggested in the Amex part of the BA Forum sticky, my wife recently moved her account to France and I found that her Amex 2-4-1 voucher (my second one really as she has no idea what it's all about and is just happy to reap the benefits!) was still posted in her 'my e-vouchers' sections but the 'redeem' button had disappeared. I haven't tried to use it over the phone, and my guess is that it is now unusable until she moves her account back to the UK.

Previous experiences of moving to and from Europe had simply involved not using the Amex card as suggested on this forum, and the voucher always remained 'live' ... but this appears to be a new development and 'downside'...

PUCCI, Je ne suis ici que pour vous servir.