Allowing rents to go unpaid is not a policy any landlord would relish.

But it is something Link Housing's chief executive Craig Sanderson is now willing to openly speculate about. "We might have to consider taking a hit, if people generally start to fall into arrears," he concedes.

He's talking about the impact of Government welfare reforms. Among the measures relating to housing benefit are changes so that people in houses deemed too large for their needs will only be awarded benefits to pay for smaller accommodation. People living on their own who are under 35 will only be offered enough to live in flats with shared facilities. There is a danger that many will be left unable to pay their rents, but unable to move into somewhere smaller.

"I'd need to discuss it with my board," Mr Sanderson says. "One option would be to forego that bit of their rent. But we have a business to run."

Link's banks, or the housing regulator, will object if the group's performance dips, he explains, although there is a precedent. "We let miners off paying their rent while the strike was on in the 1980s," he says.

But housing benefit problems are likely to affect more people, and without limit of time, he points out.

The reason we are talking is because Link Housing Group is celebrating five decades of working to bring better social housing to often deprived communities across Scotland. Last night, the group held a reception and celebration for its 400-plus staff. Founded in 1962, it now offers services to 10,000 families and individuals, mainly in the central belt.

Mr Sanderson himself has been with the company for 35 years, joining in 1975, when it still only employed six people. He became chief executive in 1987.

If he sounds less than celebratory, this is because there are tough times ahead, for housing, even though he is immensely proud of what Link achieved over the last five decades.

"Welfare reform is the biggest threat to us in all my years at Link," he says. "The bedroom tax and other measures are a big problem. Some of our tenants are now coming to say 'can you rehouse me somewhere smaller'? But our single houses are very popular, and are mostly full. What are we going to do?"

Other problems include the plan to bundle housing payments into the new Universal Credit – and pay it direct to claimants. "Much as we love our tenants, some of them will be getting that sort of money in their hands for the first time, and some of it won't be paid," Mr Sanderson says.

"The Government is also talking about asking young people to share a bedroom. We've a lot of experience of putting young adults together in shared accommodation. It doesn't work."

He is also scornful of Government claims that 80% of housing benefit applications will soon be completed online. "It's nonsense," he explains. "An advisor from the DWP met our welfare rights manager and said an online application would take about an hour. And if you don't finish it in one session, it will start again from scratch."

Aside from benefits reform, all housing associations are struggling with the conundrum of how to continue to build social housing when Government subsidies have dried up and national policy seems to favour leaving the task to councils.

Here, the picture at Link is more positive. The group was successful in bidding for the Scottish Government's heavily oversubscribed Innovation and investment fund, ending up with £8 million, enough to allow it to build 192 homes, 70% of which will be for social rent.

"Of those, 133 will be for the people we have always tried to house. We can build 200 homes over the next two years. But what happens then?"

Link can't go on building social housing without a higher level of support from Government, he says, although the group is better off than some others in the sector.

Link has built up a land bank and the group, which comprises six social enterprises and social landlords, includes a company, Link Homes, set up to build houses for sale. At one point this generated enough profit to subsidise social house building, though it is currently mostly inactive due to the financial climate. Link Living, another element of the group, generated surpluses through welfare advice work. "We have never had to put that money into funding development work before," he says.

The welfare rights work has been a huge success, he adds. "It started in the late 1980s when we noticed some tenants were getting into rent arrears due to benefit problems. We appointed a welfare rights officer then, and now we have 19. They have helped tenants, mainly older people , to claim £12m in the last seven years. We are proud of that." One disabled couple had been missing out on considerable benefits and Link managed to get these backdated, earning them a payout of £34,000, he adds.

It is just one of the innovations that have come during Link's history. By the time Mr Sanderson joined in 1975, the organisation was developing co-owned flats when the idea was still a novelty, allowing co-ownership societies to jointly own developments, with individual members entitled to a share of the improvement in the value of their property by the time they moved out.

These set-ups were devastated by a ruling that they were covered by Right to Buy, when the policy was introduced after Margaret Thatcher was elected in 1979. "We lost them all in two years," Mr Sanderson recalls.

But there were other initiatives. Link was the first housing association to offer secure tenancies to 16 and 17-year-olds and introduced supported "cluster flats" before they became commonplace. They were popular and some were leased to social work departments and the Royal Edinburgh hospital.

Link Living was set up as the group started to employ a wider range of staff, including mental health nurses and qualified youth workers. The company also got into the business of providing student housing in a link-up with Stirling University, but another former Conservative minister David Mellor "put a stop to it", he says.

There is plenty to celebrate, Mr Sanderson insists, and Link is in good shape. One possible way forward for the sector is through more mergers – and over the years Link has welcomed 11 companies into the fold. "We regularly get approaches from other organisations to see if they can join." But it is important they remain effective and any deals are carefully assessed, he adds.

Meanwhile he seems as passionate as ever to defend the tenants housed in some of Link's 7000 homes, and ensure they can sustain their tenancies. "When I started at Link people really only had to worry about rent levels. Now gas and electricity are a huge problem and prices seem uncontrollable."

The threats are so significant that Link is now preparing a letter warning tenants of the challenges to come. "It is 16 pages long and we are about to send it out to our tenants to warn them what is coming up," he explains. "It is likely some won't read it, but we have to do something."