7 day programmable digital timer. In a large "bargain bin" near the entrance. Note, the picture is not the exact item, but is the closest there is. The only difference is the placement of the dot (on/off light) above the top-left button
Apart from the one-off price, they also sell three for £10
P.S. B&Q also have a lot of electrical fittings (sockets, 3-way adapters etc) in smaller bargain bins - all priced at £1 each.