It has an all-over design in reverse stocking stitch on stocking stitch - the reverse stocking stitch areas are raised, so that you get an embossed effect. The jumper I saw was cream, but the John Lewis web site shows it in red, too. (But what about the half-tucked-in look? I read about that in The Guardian fashion column a while ago, and didn't really believe it.)
Here's a close-up of the jumper, showing the stitch pattern.
I don't know what this kind of stitch pattern should be called - I thought that it was brocade knitting, and looked in Mary Thomas's Book of Knitting Patterns to confirm. But in the brocade patterns she shows, the raised areas are alternately knit and purl. i.e. moss stitch, not reverse stocking stitch. And many of the stitch patterns used in ganseys are of this 'brocade' type.
So I'm going to call it embossed knitting. until I find out that it already has a name. It seems worth experimenting with - a easy way to get a lot of texture without making the fabric thicker, unlike cables for instance. And in fact, I did knit a thick jacket for myself three years ago with what I'm now going to call an embossed stitch pattern, for exactly that reason - I wanted some texture without the extra thickness of cables. There seems potentially a lot of scope for interesting new designs, as in this John Lewis jumper. I should do some swatches.
And I did find some smart trousers too - a successful trip all round.
(Attentive readers may remember that this has happened before - last year, shopping in John Lewis Sheffield for a pair of jeans led to experiments with two-colour moss stitch.)