What is the purpose of the £30 cancellation fee, then? The fare is non-refundable. The extras (if you purchased any) are non-refundable. All other taxes and charges are non-refundable. Why, then, when cancelling a flight do they not levy the cancellation fee?

Based on what people are saying here, the only thing the cancellation fee can be charged on or offset against - the refund of APD - doesn't happen. So why list such a fee at all if they don't charge it?

EDIT: seems the cancellation fee is charged when you cancel within 24 hours, at which stage the fare is "refundable" (less the £30 fee)