Amazon Prime Deal. This is the F version with interchangeable chuck. It has very occasionally and very briefly been a touch cheaper but rarely goes down to this according to the Camels:
I have the plain version (non-interchangeable chuck) and it's fantastic, would definitely recommend.
You need to tick the box to apply the £27 voucher.
You'll also need to be patient - currently showing 1-2 months for delivery (but we all know it tends not to be that long).