Whenever I stroll along the riverbank between Hammersmith Bridge and Hampton Court, I think of poor northerners with no nature on their doorstep. Little Hampstead Heath and tiny Muswell Hill would vanish in our great, green, southern maw. People in the north have no idea how the great crested grebe, cormorants and herons are faring on the Thames. The white bryony and purple loosestrife flower and die without ever brightening their stressed-out lives. A flock of ring-necked parakeets sitting in an ancient oak - they've probably never heard of these tropical escapees, much less seen one.