Unlocking the economic potential of mid-sized cities such as Sunderland would allow them to make a far greater contribution to growth in the UK, says Paul Swinney.

Cities act to focus economic activity, bringing people together to exchange not only goods and services but also ideas. Traditionally city centres have served as the heart of the commercial activity that occurs in urban areas, but more recent patterns of spatial development suggest they have played a less important role in economic growth over recent years.