By way of report on the question of large redemptions: I finally took the plunge and transferred £600 to Miss FF99's virgin EC account (she does exist and is under 18) late on Saturday night. This was from a 'used' CC account and the miles had posted at the old 3.2 rate by Tuesday morning (the transaction is shown in the EC statement as 'dated' Monday, 'posted' Tuesday).

Although very quick, I would guess that this involved a manual check of some sort, as it probably took a day longer than usual and the transaction was not 'dated' until Monday although carried out Saturday night.