I’ve just seen on my Amex Gold card app that they are running an enhanced sign up offer at the moment!
Get approved, spend £3,000 in 3 months and get 30,000 points. You can redeem 1000 points at Amazon for £5 so that is a £150 voucher, but lots of other great ways to spend your points including Nectar. I get I think 14,000 points in return and you can get the same when you refer a friend.
First year is free so make sure you cancel the card once you receive the offer (unless you want the other 9 months to refer friends!)
Here is my link, so grateful for any uses. Please let me know if any questions :)
americanexpress.com/en-gb/referral/fRANCWFord?XL=MIMNS