Suppose that some weeks ago you booked a flight to Rome for a return fare of £100. Imagine you had been offered, at the point of purchase, the following interesting proposition by the airline:

You, the traveller, give us, the airline, the right to buy your flights back. If we take up the option, we'll refund the original fare - and give you an extra £100.

Introducing 'callable' flights, better for the airline - and for you, continued