We're not sure who at O2 created the image for the HTC Mozart listing on product pages, but they must be an Android fan. According to the image above (and if you check out the link at the bottom of this article) O2 has the Mozart running Android, or so it seems. Clicking on the product to view more information reveals that in fact the device is running Windows Phone, but it may still cause confusion for those who aren't familiar with the device and what OS it sports.
On the other hand this could be positive in a misleading way. Should someone purchase the handset believing they'll be receiving an Android smartphone, they could be impressed with the refreshing change of to the Metro UI. Still, it should be fixed.