We last saw details about a Sony Windows Phone 7 handset in January and if new spy shots are to be believed, then the new Sony Windows Phone 7 handset will be a side slider. QWERTY Windows Phones are somewhat rare these days, with the majority being touchscreen only, but it is an area where Sony (Ericsson) has some experience. 

The new leaked images show the keyboard and rear of the device. It carries the Sony Ericsson name on the front and the logo on the rear, but that doesn't mean it isn't a future device. In recent weeks, we've seen the Xperia S with both Sony and Sony Ericsson branding, for example.

Sony Ericsson has a tendency to launch keyboard devices as "pro" models, assuming that only business types want a keyboard (see the Xperia Pro for example).

The displayed device isn't too dissimilar to the Pro either, although we note that the keyboard is open, yet the Bing search page is still in portrait, so whether we'd see Windows Phone 7 reorienting to work perfectly in landscape is a different question.

Sony is expected to be launching a number of devices at Mobile World Congress 2012 in Barcelona next week and we're expecting to see new Windows Phone 7 hardware too, so we'll bring you all the details as we get them.

UPDATE: After further research, it appears that this isn't a new device at all, it's an old unreleased model doing the rounds, no doubt caught up in the excitement of next week's Mobile World Congress. Thanks to all those who pointed it out.