Amex BA companion vouchers invalidated if you cancel Amex?

Sportacus

I just booked a flight using one of these vouchers I had earned, and was required to pay the taxes with my Amex card.  It seems if you cancel your Amex card then any earned companion vouchers are rendered unusable.  I was thinking of cancelling and switching to a virgin Atlantic card for a couple of years, worried if I’ll even be able to board my booked flight now because it also says to bring your payment card (you used) to the airport when w check in.

Sportacus

Ts and Cs are ambiguous:

1. The Cardmember is responsible for paying any Taxes, Fees and Charges relating to their Companion Voucher booking. All Taxes, Fees and Charges must be paid for using the British Airways American Express Card.

1. Cardmembers must remain eligible for this promotion at the time of travel. British Airways and Amex reserve the right to refuse to issue or honour any Companion Voucher in the event that the Cardmember is in breach of the terms of the British Airways American Express Card or the British Airways Executive Club Membership.