On a flight from MCO to LGW last Friday, I bought some perfume for the little lady, which cost a mere £20. I paid for it with a £25 VA voucher and, later on, the purser asked for my name and passport number. Any idea why? Perhaps to send me a voucher for the change?
It's a nice thought, but I wouldn't hold my breath [8D].
I think they have to keep passport details on all duty free purchases for accounting / auditing purposes.
Nick