Knock, knock. Who's there? Dunno: Britain's disappearing neighbourliness

In a bygone era, the bank holiday would have been just the moment to peer over the pants on the washing line for a catch-up with them-next-door. Instead, I spent part of Good Friday hanging around anxiously on my neighbour's front step, about to introduce myself for the very first time. My experience is not uncommon, according to new research which suggests that one in four people in the UK do not know the name of the person living alongside them. The survey claims 3.5 million Britons have never even seen their neighbour, let alone met them.

Luckily, I am not one of the 1.1 million to have called police after a dispute about leylandii or late-night noise. But London, where I live, is among Britain's most anti-social regions, with just a third of its citizens willing to describe their neighbours as friends.

This, says the accompanying press release from Findaproperty.com, is evidence of "a nation isolated from those who live closest to us". Half a century ago, writes Emily Cockayne in her new book Cheek By Jowl: A History Of Neighbours, "it was vital to establish a good reputation by acting in a neighbourly fashion. These days we can usually avoid our neighbours' misfortunes. Their lives are more detached from our own than at any time in history".

Half of the detached houses in the UK in 2000 were built in the preceding three decades. We now drive to the out-of-town superstore rather than stroll to the shop. There is no local post office, let alone a water pump. Street parties to mark the Royal Wedding of 2011 will have necessitated a lot more awkward introductions than those for the Royal Wedding of 1981. Which is why I agreed with my editor when she suggested I get to know my neighbours. By the time she suggested I get to know them with a photographer and a notebook, it was too late to change my mind.

I only recently moved in with my girlfriend in NW10, so can be forgiven for not being chummy with everyone in that postcode area. As soon as I emailed her about my assignment, however, she put me and the stats to shame: "Powell next door is really nice," she replied, going on to reveal that she knew at least three more people on our street. Then there is the couple we are friends with from a street away, and the other couple we are friends with from another street away. Someone I know from university is just down the road, she reminded me, and two of my colleagues live within about 200 yards. The man in the house opposite had a nice dog that died recently. And a world-famous comedian lives round the corner, though we are not quite on first-name terms with him, not yet.

I'm already acquainted with the chap living below us, who runs a successful barber's shop in Savile Row. (Thanks to our former plumber, he also had a spectacular leak in his bathroom ceiling recently. It's been fixed now. No police were called.) But I'd never met Powell, so I paid him a visit. He first moved to London from Jamaica in the late 1950s, and has lived with his family in the house next door to ours since 1969. Back then, he explained after inviting me in, lots of Irish immigrants lived in the area, too, and some employers still had a "No Blacks, No Irish" policy. Our homes used to belong to a brother and sister, he said.

One lady owned a row of five terraced houses across the street; now most of them are split into flats. Many of his friends have died or returned to the West Indies, and he doesn't know his neighbours as well as he used to, but he has no plans to leave, which I find reassuring. In fact, we live in a relatively neighbourly area, bordered by two main roads and a rail line to create a village-like cluster of about 1,000 households dubbed the "Kensal Triangle".

After leaving Powell, I went to take tea with Martin and Ruth Ward, who have lived in the area for more than a decade and are active members of the Kensal Triangle Residents' Association. The organisation, they explained, came about five years ago when people campaigned for the installation of a speed camera on the Harrow Road. Now they hold monthly meetings at one of the Triangle's pubs to socialise, and to discuss road safety or tree planting. The steering committee of 15 or 20 swells to as many as 70 when the agenda includes big issues like the HS2 high-speed rail line, which is set to pass underneath the area. It's not all nimbyism and cupcakes. Everyone is invited to the street parties the Wards organise in summer – whether they have lived here for years or, like me, have participated in its gentrification for just a few months.

They held a Christmas singalong last year, and are planning an outdoor film screening in September. "People say it helps them to go 'from nodding terms to chatting terms' with their neighbours," says Ruth. Martin agrees: "But it's down to the people involved, and whether or not they want to be neighbourly. Some people do, some don't."

I am suspicious of the suggestion that we live in an "isolated Britain". London is no longer a series of villages, and we are rarely on intimate terms with the people next door – but we are just as connected as ever. Our communities are not formed just by geography, but by jobs, shared interests, Facebook.

It's great to be on good terms with the neighbours, but I won't mind if we are not best friends. I'll probably go to that film screening, though. I might even take some cupcakes.

3.5m: The number of people in the UK who have never even seen their neighbours