Nokia have announced the Lumia 925, their latest flagship Windows Phone 8 smartphone, at today's event in London.

Following all previous rumours, and yesterday's leaked images, the Finnish smartphone maker has finally taken the official wraps off the phone.  It's quite similar in design cues to the previous models in the Lumia line, but it has a twist: it's made from aluminium.  The rear of the device is still made from polycarbonate, and the front is a pane of glass; but the aluminium surround marks a new shift for Nokia's material-centric design.