By Debbie McPhail
The Investigation producer, BBC Scotland
Scotland needs more affordable homes for rent if it is to meet an official target of ensuring a roof over the head of every homeless person by 2012.
The director of Shelter Scotland, Archie Stoddart, told BBC Radio Scotland that we need to make sure housing is at the top of the public spending agenda now.
Cathy Come Home was a seminal 1966 TV play about homelessness
Mr Stoddart's comments come in the latest Radio Scotland Investigation, into the state of homelessness in Scotland.
It coincides with the 40th anniversary of ground-breaking, conscience-stirring BBC TV drama, "Cathy Come Home".
First broadcast in November 1966 in the BBC Wednesday Play slot, it follows Cathy and Reg from the optimism of their early married days through a downward spiral that leads to eviction, homelessness and separation.
The final scene remains one of television's most memorable and shocking scenes - when Cathy has her children forcibly taken away by Social Services.
The film galvanised public opinion against homelessness and bad housing, with the campaign group Shelter being launched the same month the film was broadcast. Shelter in Scotland was launched two years later.
Forty years on, we don't see so many people sleeping on the streets.
However, last year Shelter estimated that more than 40,000 people were found to be homeless by local authorities in Scotland alone.
People lose their homes for a wide range of reasons, such as falling out with their family, suffering from domestic violence or being evicted by their landlord.
Currently only those in what local authorities consider priority need have the right to a home. These include families or single parents with children and certain vulnerable groups.
It's almost never young single men like 21-year-old Andrew in Inverness.
"I know at least two dozen people who are currently sleeping rough who you will never see because they don't come into the day centres and they stay away from the city centre," he said.
Malcolm Chisholm is confident the 2012 target can be met
"They've moved out into the outskirts, into the woods and are living in tents.
"These are people who feel that the system has let them down and in many ways it has."
Now, thanks to the 2003 Homeless Act Scotland, every unintentionally homeless person should have permanent accommodation by 2012.
Archie Stoddart, director of Shelter Scotland said: "The 2012 target will give single people the same rights to housing as families with children, ending decades of inequality, and that is why this legislation is so important."
The man in charge of turning legislation into bricks and mortar is Communities Minister Malcolm Chisholm, who is confident that the target can be met.
Mr Chisholm said: "The thing that people most obviously think about in relation to homelessness is having enough houses and that is absolutely basic so we have got rising investment already in new houses - 7,000 new starts this year, rising to 8,000 in 2008."
While the minister is happy to highlight the Scottish Executive plans to build these new homes in the next two years, Mr Stoddart believes they still won't be enough to meet demand.
He said: "The 2007 spending review must commit more money to increase the supply of affordable homes for rent by 50% - that translates to just under 3,000 more affordable homes a year than the Scottish Executive is currently proposing."
Scotland's local authorities are the ones charged with implementing the legislation.
But in pressured areas like Edinburgh, Glasgow and parts of rural Scotland, the housing shortage is already acute.
For every house built by the public sector, three leave the housing stock through the Right to Buy.
Shelter says 3,000 more affordable homes must be built each year
Independent councillor Peter Corbett represents Merkinch in Inverness. His ward contains the largest amount of public housing in Inverness but there still aren't enough homes to meet the demand.
Mr Corbett said: "Since the days of Maggie Thatcher when they sold the council houses, we never replaced these houses and the people that need houses now are growing and growing and we're nowhere near keeping up with them.
"If the 2003 act was to provide everyone with a home, it's certainly not doing that."
Mr Stoddart added: "Scotland needs more affordable homes for rent.
"And we need to make sure the money is available to build them when the next big wedge of money is carved up next year.
"Scotland looks at its three year spending plans next year, which takes us up to 2011. It'll be too late by then.
"We need to make sure housing is at the top of the agenda now. The executive and local authorities are working towards the 2012 deadline and we applaud that but we need to see it become a reality."
You can hear Radio Scotland's Investigation into homelessness with Ken MacDonald on Monday 4 December at 0850 GMT.