Focus: They sleep on the night buses, or beg sofa space from friends. They have nowhere else to go. They are the hidden homeless

There are 380,000 such men and women in Britain, who are not listed on the records so cannot get help, but who have no homes. We may not see so many rough sleepers these days but the new underclass of single homeless people is growing, finds Katy Guest

Erna is homeless. You won't see her in a shop doorway, though. She doesn't want change for a cup of tea. She doesn't look homeless, and the authorities do not think she is vulnerable enough to need help - but for eight years Erna has toured the hostels, ridden the night buses just for somewhere to sleep, and outstayed her welcome on so many sofas that she has lost count.

Erna is homeless. You won't see her in a shop doorway, though. She doesn't want change for a cup of tea. She doesn't look homeless, and the authorities do not think she is vulnerable enough to need help - but for eight years Erna has toured the hostels, ridden the night buses just for somewhere to sleep, and outstayed her welcome on so many sofas that she has lost count.

"I'm moving, moving, moving," says the 58-year-old, who has a business plan and wants to start a Caribbean restaurant, but can't get backing until she gets an address. "All I want is a place of my own."

When she left her violent husband, Erna became part of a growing underclass, the hidden homeless: these are the rapidly growing number of people left behind because of the soaring cost of renting (let alone buying) somewhere to live. There are 380,000 people like her in Britain, according to the charity Crisis - men and women who do not appear on government records as homeless, but who have no homes.

Walking through any city centre, you would be forgiven for thinking that the problem had disappeared, or at least diminished. There are not as many people sleeping rough as there used to be. But homelessness is worse now than it was in 1997 (the year Labour came to power and Erna left home), according to a cross-party group of 25 MPs calling on the Government to do something about it. An early day motion last week expressed alarm at a problem that seems to have been swept off the city streets but has not gone away.

The hidden homeless are adults with no dependent children and who are classed by the authorities as "non-priority" cases. The problem is that nobody has a responsibility to house them - so most don't bother signing up for help they know they won't get. Local councils don't know how many of them there might be. The Government has no plans to find out. But the number is large, and it is growing. By 2010, Crisis estimates that there will be 650,000 Ernas shuffling between the sofas and floors of relatives and friends. By 2020, there could be a million.

Single people are suffering the most, says Crisis. The growing number of single households and the lack of any social housing being built for them is contributing to a potentially huge problem. "Traditionally, single people have not been important politically," says Tarig Hilal, the policy manager at Crisis. "But this is a growing part of the population, and likely to increase. Some pretty big changes in the make-up of our society are not being recognised."

While the numbers of pensioners, parents and children in poverty have dropped under this government, there are significantly more childless, single people living in poverty than before: about 3.3 million.

"If you are single, living on your own is a more costly affair," says Hilal. "You get fewer benefits and fewer tax credits. Services, support, legislation and policy are not designed to help you. Take the most vulnerable of that group, and the picture starts to emerge of how these people run into problems. A lot of the people we deal with feel very isolated."

Yvonne is one them. The 30-year-old left a good job in an art gallery to come to London and live with a man, who turned violent. She had to leave - it was his flat - but she had nowhere to go. Even when she found a full-time job, it did not pay enough to enable her to save for a rent deposit in the inflated London housing market. So she has moved from hostel to hostel, looking for a break. Many people in her position do not appear among the 200,000 names on the official list of homeless people as they have not registered with (and been accepted by) their local authorities.

"When we came up with the figure of 380,000, the Government said, 'What a load of rubbish'," says Guy Palmer, the director of the New Policy Institute. "So we asked them to come up with their own estimate. They say they can't because they don't collect any data on this."

But homelessness charities think it is about time they did. The Scots have. There was a startling leap in the official number of homeless people north of the border in 2003 when the Scottish Parliament widened the criteria. Instead of being alarmed by the figures, the Executive rejoiced in being able to help more people. "To a considerable extent, our experience shows how big the hidden homelessness problem is," says a spokeswoman. "But that doesn't mean we catch everyone, even now."

Crisis is now raising funds to run a pilot census, in order to show the Government that it is possible. "We count the most ridiculous things in this country," Hilal points out. "If Tesco can count the number of melons it sells, we can count the number of homeless people."

In Parliament, MPs are lobbying for a change. But as you ride the night bus home, that person nodding off in the next seat may well be dreaming of somewhere to lie down. As Erna says: "I just want a place of my own."

The sofa surfer

Erna Woodley, 58

I went through 19 years of domestic violence. I don't like divorce because I have a Christian faith, but I had to leave home. I have a son who is 20 and at university, and a daughter who is 23. My children have a good relationship with their father, but he really treated me very bad. I went to the Caribbean to sort myself out and then came back. It will be eight years in June since we separated and I still have no place.

To start with I lived in shelters. I couldn't get housing from the council; they told me I was a non-priority, even though I had a letter from the doctor. I was sleeping on the buses. I moved so many times from people's places. From 2003 to September last year I was sleeping at friends' houses, on the sofa, in a spare bed or on the floor. They would all treat me very nice but after a few weeks they would decide they don't want me in their home. They were not always supportive in the end, and I desperately wanted to make my own way in life. Now I'm staying in someone's place in Maida Vale. She was also homeless, and I met her in a women's refuge. It's OK but I just want a place of my own.

Before I can get a job I need an address. And before I can get an address I need a job. I feel like I am stuck. I have everything planned for my own business - I have a business plan and a business adviser, and I am going to set up a Caribbean restaurant. But I can't do anything till I get my own place. Apparently there are places in Kent to house women like me, but it is a long wait and it is very painful. Until then it is just moving, moving, moving.

The low-paid worker

Yvonne Powell, 30

You get caught in a loop. The last job I had was full-time, and it paid what I thought was a pretty decent full-time wage. Although I was earning enough to be off benefits, I still wasn't earning enough to be able to save for a deposit somewhere. I couldn't afford private rent, not even for a bedsit.

I am frantic to be independent. As a friend said, in London it is almost impossible not to be in some sort of social or financial underclass, because you have to earn so much money before you can afford to rent your own place. Potential employers see you as a transient character who's not worth training because you'll move on, or worse, someone with such a huge problem that you'll be no good at the job.

I have been hidden homeless for three and a half years. I gave up a job in an art gallery to move to London and be with a man, but I had to leave him because he was violent. It was his flat, so I had nowhere to stay. I went to a women's hostel but I couldn't stay there long. The next place had a huge problem with violence and drugs. The place I am in now is quieter, but it can still be challenging.

I have put a lot of my life on hold, especially my love life, because you can't be in a meaningful relationship with someone when you're vulnerably housed. Practically, what can you bring to a relationship? Being in a hostel is like living in a glass box. While you are protected, you are also isolated. And it's like watching the rest of life and the rest of the world going on around you and yet not being part of it. I'm tired of living on the other side of the glass.

The night bus rider

Graham McEvoy, 58

I gave up my job as a purchasing manager for a big American company to come back and look after my elderly parents in March 1998. Three years later they both fell over and went into a nursing home on the advice of the social services. They never came out. After they died, the nursing home had me evicted so my parents' house could be sold to pay off the bills. I spent the winter living in and around Heathrow airport. I had most of what I wanted in a suitcase, so I looked like a traveller anyway. I just waited for people to put their heads down and settled down next to them. But after a while, I started to get noticed by the police. I had no reason to be there, so I was trespassing.

I slept rough, then went riding on the night buses. In the winter I'd get a seven-day bus pass and use it for travelling around to keep warm and dry, especially at night. I would just ride and ride to the end of the line. I used to use public toilets and John Lewis to wash and shave every day, to try not to look like what I was. I went cold-calling, looking for jobs like washing up or bar work. I didn't get any.

Where I am staying now is comfortable, clean, safe and secure, but the postcode says it is a hostel, which for a long time made it impossible to get a bank account. Without one, it is hard to get work. Very few people pay in cash these days. But I am trying very hard to find a job.

People like me are invisible. The Government has no idea of the enormity of the problem. If you're out of the way, on a night bus or on a sofa, that's just it: you're out of the way.