We live in strange times. No doubt you’ve read about the remarkable seven-bedroom mansion that has just sold for £35m in leafy Hampstead, north London. Yet, while there has been plenty of coverage about its interior, what hasn’t been so widely reported is that only the chosen few ever got to see it.

Not only did prospective purchasers have to pay £1,000 for the privilege of reading its leather-bound brochure, they had to be vetted before being allowed in. Palladio, the home in question, sits in an exclusive gated cul-de-sac, and its high-roller neighbours are seriously protective of their private patch.

Yes, this is an extreme example from the top end of the property market, but it demonstrates a growing trend: exclusion. In the past decade, more and more private gated communities have been created: fenced housing developments to which public access is restricted, with hoi polloi kept out by state-of-the-art security. All well and good, if you value your privacy or want to escape the paparazzi glare, but has anyone stopped to consider the wider social effect?

There are more than 1,000 gated communities in Britain, many of them encircled by 6ft-high brick walls and iron fences. Electronic gates, 24-hour security guards and CCTV keep outsiders away. Inside these wealthy enclaves – and they are always wealthy – the streets are spotless and the landscaping is lush. The marketing is full of talk about safety, community spirit, exclusive services and private amenities such as pools, gyms and even shops. In an era when our trust in government to provide community and infrastructure services – and, indeed, our trust in each other – is at an all-time low, closed neighbourhoods are highly seductive. Privacy also means exclusivity, and thus increased property values.

There is, however, a flip side. Such enclaves are designed specifically to exclude people whose class or culture doesn’t fit with the aspirations of the developers or the buyers they target. The bottom line is that they separate rich from poor. Now, you may believe that this is an excellent plan, but isn’t it time we stopped to think about the long-term effect on society?

Gates send an unwelcoming message: complete distrust of the world outside. Imagine not being able to walk along what should be a public street because it is blocked off: this hardly encourages an open, cohesive society, does it? Meanwhile, those living on the inside are buying their own security – and, in doing so, I believe they are undermining law and order. Only despots and dictators should have private security firms. What happens if there is a robbery or an assault? Do police not go in because private security guards are already on the scene? Who is really in charge? Such behaviour makes society more fragmented than it already is, and doesn’t say much for the world we live in.

Bow Quarter is a gated community created in 1992 on the site of a former matchstick factory, just off Bow Road, in east London. This seven-acre complex of 714 flats and 19 houses is walled off from neighbouring streets, employs security guards 24/7 and is peppered with infrared surveillance cameras. Get past the gates and the security guards, then sign in, as all visitors must do, and you’re in a different world. Outside, Bow Road is noisy, grimy, a bit edgy, bustling and multicultural. Bow Quarter, by contrast, is peaceful, litter- and graffiti-free and – of course – feels safe. It has its own leisure club, supermarket, bar, restaurant, post box and communal garden. With such facilities, residents need never mix with the locals.

Nor are gated enclaves confined to the capital. In Cheshire’s golden triangle, Premiership footballers pay premiums to hide away in places such as St Hilary’s Park, in Alderley Edge, or Pownall Park, in Wilmslow. Surrey has developments such as Windlesham Court and St George’s Hill. All have their own codes of behaviour, barrier entry systems and private guards.

Meanwhile, the residents of some streets surrounding gated estates are forming “associations” and seeking to block access. Public roads that you and I used to be free to drive on – and that our taxes helped to pay for – have barriers on them, and only residents of the roads in question may use them.

All this is despite government spouting forth about the importance of social integration as Britain’s population continues to rise. Our towns and cities are becoming more crowded; our personal space is being eroded. No wonder we all yearn for more privacy. But segregating communities is not the way to go. A them-and-us scenario can only foster resentment and distrust.

Lord Layard, a key government adviser on social issues and emeritus professor at the London School of Economics, is horrified by the rising popularity of gated communities. “The need to build, and the desire to live in, these gated communities is a terrible reflection on society,” he says, adding that the idea of barriers blocking off roads that were once public was “scandalous”.

“Demonstrating a lack of trust breeds an even further lack of trust,” he says. “It is self-replicating.”

Text and e-mail already mean we don’t talk or develop relationships like we used to. An unhealthy side effect of modern living is the reduction of contact with other people. Where will it all end? Will we all live in individual pods, in a virtual world entirely insulated from real life?

Another effect of gated communities is effectively to privatise what should be civic responsibilities, such as refuse collection, street maintenance, recreational facilities and security. What next? Will those who live in such places have their taxes cut? Will they be able to opt out of being covered by local-authority bylaws as a result? Will we end up with a series of independent mini-states run by the dictators of housing associations?

Gated communities are a desperate, if understandable, response to decreasing trust and investment in our society – and they will end up doing even more damage. Storm the barricades now.

Phil Spencer is CEO of the home-search consultancy Garrington; 020 7376 6780, www.garrington.co.uk

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