London, England - Although originally from Bergen in Norway, Viv Askeland has lived in London since 1979. After her marriage broke up, she found herself living on the streets of the capital for six years.
"Everybody has a different story," she says. "It can be a lost job, the breakdown of a relationship, losing a house ... Anything can send people on a downward slope from which they end up homeless."
Mike O'Hara's story is quite different. He had enjoyed a successful career as a senior manager in facilities management until the economic recession hit in 2008. He lost his job and, two months later, his house.
"I decided to go to to Vietnam to 'ride out' the recession," he says. "I found teaching work there. Things were going well but then I became seriously ill and was hospitalised."
After two months in hospital O'Hara lost that job and was left with a huge medical bill that cost him all his savings. He returned to the UK penniless. Denied social security benefits because he had been out of the country for more than two years, O'Hara was left homeless.
But, in recent years, Askeland and O'Hara have found new, if unusual, work which has helped them to get their lives back on track and to put roofs over their heads. Both work for 'Unseen Tours' - a social enterprise through which homeless and formerly homeless people offer London's tourists an alternative street-level tour of the city.