The Grand Union Canal is often overlooked by Londoners. It doesn't run through the trendiest parts of town and parts of it look kind of neglected and rubbish-filled, especially in the winter months. But it's a quietly gorgeous body of water, running from London to Birmingham and dotted with barges and houseboats all the way along. You might not use it as a transport link the way you would some more central canals but for a solitary walk just for a walk's sake there's nowhere finer. Head west from Boston Manor towards Brentford and you'll pass gorgeous bridges, muddy rabbit-filled fields, cats sleeping on top of potplant-covered long boats and almost no people at all. If you make it all the way to Brentford, you'll pass through disused shipping sheds that open out onto a sparkling little harbour where you can sit in the sun and be bothered by no one.