Over 10 million people pound the pavements of England's two-millennia-old capital most days, but zoom out from the gritty city streetscape a little, and London looks leafier and more verdant than many visitors and inhabitants realise. Boasting 3,000 public parks - ranging from big breathing spaces to secret little oases - London is Europe's greenest major metropolis. This guide seeks out the serener side of the original Big Smoke. All set within the M25, these 30 routes ramble across commons, greens, parks, hills and heaths, wander along waterways and through woods, meeting London's lively wildlife and unearthing endless surprises along the way.