Ratmageddon: Why rats are overrunning our cities

Rats are multiplying at speed in urban areas. So, what's really behind the boom - and is it now unstoppable?Rats are multiplying at speed in urban areas. So, what's really behind the boom - and is it now unstoppable?Rats are multiplying at speed in urban areas. So, what's really behind the boom - and is it now unstoppable?