A report on institutionalised child abuse in Scotland over a 45-year period has been delayed for a further six months.

Abused former residents of children's homes who gave evidence to the review were expecting to see the results in March.

Instead, a new date in September has been requested, putting it a year behind the original schedule.

The latest delay means the report will not appear until after the Holyrood elections in May but the man conducting the review, Tom Shaw, insisted yesterday it had been at his request, because of the volume and complexity of the task.

Campaigners believe the number of former residents coming forward has also exceeded all expectations. They are continuing to press for a public inquiry into the affair and hope that if there is a change of government it will improve their chances.

The matter has dragged on since 2002, when a former resident of a children's home petitioned the Scottish Parliament to investigate abuse going back decades.

Two years later, Peter Peacock, the then Education and Social Work Minister, refused a public inquiry.

Instead, the victims received a blanket apology from First Minister Jack McConnell for the abuse they had suffered and Mr Shaw, retired chief inspector of training and education for Northern Ireland, was asked to conduct an independent systemic review. He estimated last September as the delivery date.

He said yesterday he was looking at the systems in place between 1950 and 1995, rather than individual institutions.

However, he and his researchers have heard a litany of suffering, encompassing beatings, cruelty and sexual abuse over decades in children's homes run by the churches and at Quarriers in Bridge of Weir.

"The reason I have asked for more time is that the work I am doing is looking at a very complex legislative and historical environment," he said. "I am convinced it will take a few months more to do the work in a way that will be complete and satisfactory."

Although unwilling to go into numbers of interviewees at this stage, he said: "The system across the 45 years is very complex in terms of the legislation and the size and number of institutions, and it was difficult in advance to anticipate fully how long it would take. It was an estimate based on the best information available at the time.

"It is clear we have received a great deal of information. I am looking at systems and not individual institutions and what systems were in place, how they were monitored and what was the experience of the residents.

"I have invited former residents to make a contribution and a number have chosen to do that. I am still receiving information from a number of people and I would like to keep that open."

David Whelan, 49, a former Quarriers boy who has been campaigning for a public inquiry, said: "What I understand is that more people have come forward than was anticipated and there is more investigative work.

"It means we are looking at Quarriers in depth and the report is going to be made public, which is welcome.

"Our concern is that it still requires a judicial inquiry, and that the people who were in these institutions are not getting the support they require - people with mental health issues.

"The Executive say they can get this and they can get that but, in practice, they can't. There have been few tangible results for victims. It has been mismanaged."

INCAS, a survivors group, suspects the inquiry was refused over fears that failure to protect children in care institutions could lead to lawsuits costing £50m. A number of cases are going through the courts and some staff, including David Whelan's abuser, have been jailed.