An update: this lunchtime I went to test-ride the Whyte 805 and a 'cross bike, which turned out to be the Genesis Croix de Fer '14 model.
The Whyte felt great - light and responsive. It's well-equipped, particularly at £850 with the 15% discount.
In contrast the brakes on the Genesis weren't great and it wouldn't offer much over what I already have.
So, Whyte 805 ordered and is being held until the C2W starts at the end of this month (it had to be ordered in the next 10 days to get the discount).