He presents an exploration of London's fauna and flora at street level.
He encounters two plants so associated with the city that they are now named after it.
Matthew Parris continues his exploration of London's wildlife by considering the species which live on - and in - the city's rivers.
The Thames' days as a dead, polluted sewer are thankfully long gone and once again salmon are slipping upstream past Kew Bridge and eels are part of the river ecosystem rather than just a speciality of pie and mash shops.
Matthew discovers that London is built on one huge wetland, gets an angler's view of the recovery of London's fish stocks and is introduced to the unusual pleasures of eel-stroking!.
Matthew Parris continues his exploration of London's wildlife by turning his attention upwards towards the species which inhabit the rooftops.
He takes a look at the private life of the London pigeon - still going strong despite being banned from Trafalgar Square - and he investigates the 'greening' of the City's roofs to create living space for birds and insects among the high-flyers of London's financial and business districts.
Matthew Parris continues his exploration of London's wildlife with a look below the Capital's streets.
He discovers rare bats in disused London Underground tunnels and takes a closer look at the lives of the mice he's spent many hours watching from Tube platforms.
But these aren't the only animals to adapt to the warm habitat which exists far beneath the London streets: the Underground also has its own unique species of biting mosquito.
Matthew Parris concludes his exploration of London's wildlife with a look at the exotic and unusual species which are quietly taking up residence in the city's parks and gardens - from the Australian beetle which turned up in a Chelsea pub to the alien invaders of the plant world.
Matthew also tries his hand at urban fox-watching and he looks ahead to the wildlife of London in a century's time.