Found this in John Lewis Southampton in-store, could well be national but a clearance line. Popped in for a look and ended up spending £300+! The keyboard's RRP is £34.99; JL were doing them for £15 and had quite a few left, brand new and sealed. Reviews are solid (but not perfect, seems to be more from people trying to use them as office/heavy-duty units) but seem to be better made than the Logitech K400 - I will probably go back and buy another once I've had a play with the first one. Couldn't see it online but Microsoft link is here:https://www.microsoft.com/accessories/en-gb/products/keyboards/all-in-one-media-keyboard/n9z-00006
If you are popping in there were other deals worth a look - I got a Samsung C430W colour laser printer for £35 (open box) and a UE Roll 2 for £25 (missing box and manuals). Stacks of Samsung-branded cases for Galaxy S5 and Tabs if you like manufacturer-branded stuff, lots of reduced TVs. Had to get out before I maxed the credit card!
Hope this helps some of you.