Santander are offering £20 if you go through Topcashback and open a current account. Don't need to switch, just open an account.
You need to make 30 debit card transactions over 60 days, so I plan to put 6 individual bananas through every week or something similar.
Theyre also giving £100 Amazon voucher.
I've just done it and was surprised I got accepted as I already have a couple of Santander accounts. The £20 is already there.