£1295 at John Lewis including a 3 year warranty. This is on the Microsoft Store currently at 10% off full price and still costs more at £1,439.10!
This is the cheapest Book I would personally buy, having the dGPU in the keyboard section and a reasonable 256Gb SSD.
So, 3 year warranty and £140+ cheaper than MS's 10% "deal". I ordered one!
Edit: Possible to get a free XBOX One S and FIFA 17, or an XBOX One S with Minecraft for £20 LESS if you go for a bundle. Out of stock at time of writing this but I managed to get one, and cancel my original order, in some brief moment when they came back into stock. So keep an eye out.