The number of people living in squats in England and Wales has risen by 25 per cent in the last seven years, according to new figures. But contrary to popular belief, greater numbers of squatters are now professional, middle class and upwardly mobile.

The Advisory Service for Squatters (ASS), a voluntary group, believes there are as many as 22,000 people living in squats, up from 15,000 seven years ago. In 1995, estimates put the number at 9,500. The figures are believed to be a conservative estimate.

Experts say the increase is fuelled by an increase in rents and house prices, a decline in public housing stock and tighter restrictions on mortgages, meaning there are fewer opportunities for people to secure homes. This, together with a greater number of vacant properties as a result of repossessions or buy-to-let landlords unable to rent properties, has resulted in more squatting opportunities.

Agencies dealing with squatters are reporting increases in the number of cases they handle. Will Kahn, senior adviser at Tenant Eviction UK, said: "We have seen a rise in the cases relating to squatters in the last year or so. I would say this increase is a result of the recession, because there are more empty houses. We're dealing with seven to eight squatter cases a month. A couple of years ago, we were doing two a month, so it is a significant increase."

Squatters were typically associated with parts of London or other big cities. But many solicitors are now seeing a shift towards smaller towns and cities throughout England: "You do see it happening in towns such as Leicester, Peterborough, Norwich, and we've had a few cases in Bedford," said Gail Sykes from Buckles Solicitors. "We are seeing a different kind of squatter. You used to have a lot of travellers moving in and camping on land. We now tend to be dealing with people breaking into or obtaining access to clients' vacant properties. We've seen that change within the last 18 months."

Many organisations said they were also seeing a variety of people squatting – from young professionals who want to save money to art students seeking space for their art work.

A spokesman for ASS said: "More people are thinking about squatting because of the recession. We get calls from a very wide spectrum of people. You certainly can't tell what type of person is going to end up squatting. Art students, for example, need more space than they could get by renting."

Definitive figures on numbers of squatters are hard to come by, as police and many local authorities do not keep records.

Squatting is lawful in England and Wales if entry to an empty property is not forced resulting in criminal damage. Owners of the squatted building are forced to take civil action through the courts to remove the unwanted occupants. In Scotland it is illegal to squat in a property. If someone is found to have illegally entered a property, the police will take action.

Experts say the new generation of squatters have a greater understanding of the law and how it can protect them, helped in part by sophisticated legal advice available on the internet.

Ben Gower for UK Bailiff Company said squatters had become legally savvy. He said one person would walk up to a property, break a window and walk away. Then another would come along and enter the property through that window and put up a "squatters' rights" notice. "Previously squatters were people who didn't have money and found empty premises," Mr Gower said. "Now they break in and others put up a section 6 notice saying 'we are squatting on these premises'."

At the squatting movement's height 40 years ago, many occupied buildings as a badge of their political activism. Nowadays, squatters are more likely to be driven by financial necessity rather than social concern.

In 1994, the then Home Secretary Michael Howard, said: "There can be no excuse for seizing someone else's property for however short a time." Measures in the Criminal Justice Bill were then designed to deal a blow to squatters.

The coalition government has promised to act promptly now that squatter numbers are increasing. They have promised to give greater powers to councils and landowners to better deal with squatters. The communities minister, Bob Neill, said he is working on proposals to create a new criminal offence of intentional trespass. He has also said: "We are also committed to dealing with the problems caused by empty properties and are exploring a range of measures to help local communities bring empty homes into use."

A spokesman for the Advisory Service for Squatters, said: "If land and property is not being used, it can be beneficial for the neighbours and community that it is used and doesn't become an eyesore. The Criminal Justice Act only served to make squatters more insecure. The more secure they are, the more energy they are going to put into the community. I don't think the Government will criminalise squatting in any simplistic way."

Case Studies

The Squatter: 'Squatting could be seen as a gap-year activity'

Carys Jones, 21, has been squatting in a disused warehouse in Nottingham for six months with between 10 and 20 others. She works as a secretary for the NHS and is taking a degree in English literature. She started squatting after becoming homeless. Her squat faces the daily threat of eviction.

"There are lots of pros to living in a squat, beyond the financial ones. Squats hold community events, give out meals and actually improve difficult neighbourhoods. You have to consider the ethics of squatting. Our building is a Grade II-listed Victorian warehouse, owned by a private landlord, which has been neglected for years. I would never advocate going into someone's home. Squatters aren't unemployed heroin addicts. Lots of my housemates work. There are cons, however: people break windows and scream 'dirty squatters!' In 10 years time, I probably won't be squatting. I'm working and studying, so I'll probably be settling down. Squatting has been a really good learning experience. I feel a lot more confident and I can tackle anything. It could be a gap-year activity."

The Victims of Squatting: 'These were not people who were poor or homeless'

Professor Phil Reed, 47, and Dr Lisa Osborne, 46, bought a home in Brighton in 1995. They lived there until 2001. Moving to Swansea because of work commitments in 2003, they used the property to store their personal belongings. In 2008, not having been to the house for some time, the couple received an electricity bill for £2,026.67.