Excuse me, may I camp in your garden?

Thanks to a new website - and a supply of baked beans – Aaron Miller's dream of walking the Capital Ring came true

I was standing on a packed commuter train headed for London with a rucksack on my back and a stranger's address scribbled on a piece of paper in my pocket. Suited business people stole the occasional glance from behind laptop screens and morning papers. They were trying to get to work. I was trying to get to my starting point on a 78-mile walk around the capital.

It all began with the launch of a new website called Campinmygarden.com. The idea is people register their private gardens as temporary campsite accommodation. It's a little like couchsurfing (where homeowners invite visitors in for the night) but without the couch. Browsing the site, it struck me there was an opportunity here for an adventure too exciting to miss. Long on my wish list of travel opportunities has been the Capital Ring, a 78-mile footpath that traces a circumference of London. What better way to walk around the city, I thought to myself, than camping in Londoners' back gardens? I toyed with the stranger's address in my pocket nervously. I was about to find out if I was right.

The route is broken into 15 easy sections, each averaging about five miles, and can be done in any order or combination. The starting point I'd chosen was the south side of the Woolwich foot tunnel in East London. From there the Ring follows a clockwise route via Crystal Palace, Richmond, Highgate and Hackney, before finally running back through the Woolwich foot tunnel.

I headed east beside the river, and just before the Thames Barrier and the O2 Arena I followed the green Capital Ring route markers onto Woolwich High Street. The path is well signposted but within minutes I somehow managed to get lost. I must be the first person in the world to have taken a compass bearing on Woolwich roundabout. Back on route, I eventually found myself at Sevendroog Castle, an 18th-century triangular gothic-inspired tower built in memory of Sir William James's exploits for the East India Company. Barry Gray, a local doctor and trustee of the castle, told me they were about to start restoration work and offered to show me why. We climbed three spiral layers to an open turreted roof and suddenly we were above tree level - the city opening up around us. I mapped the route of the Ring in my mind, daunted by the scale of it all.

After lunch at the top of Shooter's Hill surrounded by the oaks and silver birches of the 8,000-year-old Oxleas Wood, I walked south, passing Eltham Palace, the childhood home of Henry VIII, before heading down St John's Walk – the old path that links the palace to the hunting estates of the south.

Just beyond Beckenham Place Park the dark clouds that had pursued me ominously finally broke. I ran through the dinosaur sculptures of Crystal Palace, spurred on by the text I'd received from my first garden owner: "Hope you're not too wet, there's a beer with your name on it when you get here."

Despite the text, it was with some mild trepidation that I stepped through the door to the top floor of a large detached townhouse, with colourful rugs adorning wooden floors and a collection of art hung proudly among vaulted attic ceilings. But my anxiety soon faded away when I was brought into the kitchen, where a tasty spread of cheeses was neatly arranged beside a selection of designer beers. The owners turned out to be a twentysomething couple called Vienna and Rick. We wolfed down Camembert and Stilton, then beer turned to wine, and the conversation flowed from art and music to travelling and why on earth they would want a stranger staying in their back garden. "It's all going in the India fund," Rick told me. "That's our next big trip."

I started to feel quite at home, as if I was round at a friend's house for dinner; except my actual dinner was in two tins in my bag and I still had to pitch my tent. Later, as I scooped spaghetti and baked beans into cold unbuttered rolls, it occurred to me that sleeping in someone's back garden is a bit like being a naughty puppy. I couldn't help but mentally paw at Vienna and Rick's door.

From Crystal Palace the Ring heads steadily west through Streatham, Balham and a seemingly endless parade of leafy residential streets. I felt like Bear Grylls making a guest appearance on The Truman Show. As I crossed Wimbledon Common and Richmond Park, the rain came – in earnest this time.

Late in the afternoon I arrived at a two-up-two-down in the suburb of Feltham, West London, and pitched up next to the shed and compost heap. Owner Nigel offered moral support by joining me for a bracing camp-stove brew. I wondered if he was nervous having a stranger pitch up in his back yard. "Actually if you think about it, it's quite safe because we're inside, we can lock the door," he told me with a mischievous grin. "In some ways it's the camper who needs to watch out."

Just as I was contemplating another night of baked beans, Nigel's wife Jackie – a native Singaporean - invited me to for dinner. "This is all home-cooked traditional food - you won't find this in a restaurant," she told me, as we sat down to a banquet fit for a king, let alone a poor camper.

The next day the path continued to ebb and flow between gritty sections of grey urbanism and wild oases of green tranquillity – the experience of each somehow made more powerful by the contrasts. Syon House seemed even more impressive next to the modern high rises of the A315 on its doorstep. Later that afternoon, after walking north from Brentford beside the Grand Union Canal and the River Brent, and with almost 20 miles already under my belt, I picnicked in Fryent Country Park with a view of Wembley Arch.

My last night was spent in Highgate, north London. I staggered in late, mumbled incoherent hellos and pitched my tent beside a washing line, a slide and a deflated football. As I discovered an infestation of garden snails in my tent, I was painfully aware of my hosts tucked up in a slime-free bed. The following morning, with the sun in my eyes and dandelion seeds in the air, followed the water of the Lee Navigation as it drifted past Walthamstow and Hackney Marshes. I had lunch at just a stone's throw from the Olympic Stadium and then followed the elevated Greenway for five hard final miles to Beckton Park.

As the first glimpses of the Thames appeared I remembered what Jenny Humphreys, route manager of the Capital Ring, had told me before I left. "Because I've walked the Capital Ring," she said. "I feel like I get London, how it's all sewn together." Now I understood what she meant. My shoulders and hips ached from the weight of my bag, my feet were blistered and bruised, but I felt I understood the sheer scale of London in a way I never had before.

For more information on the Capital Ring walking route, see tfl.gov.uk. Audio guides and maps can be downloaded at Walklondon.org.uk