As far as I'm aware if you book a ticket using Avios, you'll get the landing fees and taxes (500 quid's worth for NY) back (including a refund of Avios) right up to the last 24 hours before wheels up.

The only cost is about 50 quid cancellation fee...correct...??

If you book a flight using Avios and use your Amex voucher to bring someone along for the ride, then what happens...?? Do you get recredited both passengers landing fees etc, the Avios and the Amex voucher...??

Please let me know before I do this or it'll be an expensive mistake if this trip goes south (rather than west I suppose...!!) for some reason...Chris