You will receive £10 cashback when you make a £20 purchase at amazon.co.uk before 6th December.
To see if you are targetted, log into your online Amex account here and look under ‘Offers’ on each of your online statement pages. My wife and I have five Amex cards between us and it was only showing on her Amex Gold.
Your odds are not great, unfortunately, but it is worth a look.
Only 15,000 registrations are allowed, so click ‘Save To Card’ immediately. You can then make a purchase at your convenience before the deadline of 6th December.
However, the easiest thing to do is to go to this page and top up your Amazon account balance with £20. This is a new feature and is quicker than buying an Amex gift card and emailing it to yourself. If you do this, you are not taking any risk that you forget to make the £20 spend in time.