Originally Posted by
LCY8737
So assuming OP had been downgraded and insisted on travelling on the next available service in the cabin they had paid for, BA would not owe anything?
Correct. And reason is the distinction between compensation and reimbursement. Downgrades are permitted to airlines, if it happens you are not compensated, but there is a reimbursement formula, known as Mennens, that applies. BA can actually decline to rebook you, though in reality they will offer this, but the reimbursement formula doesn't apply. You may be able to get a customer service gesture, but at the heart of this is that downgrading is an allowed outcome.