Correction 10 November 2012: The BBC has apologised unreservedly for broadcasting a report on Newsnight on 2 November over allegations of child abuse which transpired to have involved a case of mistaken identity. As a result the video of the original report has been removed from the website. More details can be found here.

A man who was sexually abused as a child in care in Wales has called for a new investigation into the true scale of the abuse and who was involved.

Steve Messham was one of hundreds of children abused in the 1970s and 80s - exploitation brought to light by the Waterhouse Inquiry Report in 2000.

But he told BBC Newsnight the inquiry uncovered just a fraction of the abuse.

He and another victim also told the BBC a leading Thatcher-era Conservative politician took part in the abuse.

Since the Jimmy Savile sex abuse allegations surfaced, politicians have been raising questions about other historic cases.

During the 1970s and 1980s almost 40 children's homes in north Wales were the scene of horrific child abuse in which youngsters were raped and abused by the very people who were paid to look after them.

In the early 1990s, allegations of the abuse started to surface and in March 1994 Clwyd County Council commissioned an independent inquiry into claims of widespread abuse across north Wales, centred around the Bryn Estyn care home.

Professor Jane Tunstill, who was on that inquiry panel, told the BBC in 2000 that along with a "litany of abusive practices going on in the home on the part of the care staff" there were rumours that people outside the care system were also involved in the abuse.

'Shadowy figure'

However, the inquiry's report was never published and the copies were pulped to ensure that the local authority was able to maintain its insurance cover.

In the wake of this, and amid growing public pressure, in 1996 the-then Secretary of State for Wales, William Hague, ordered an inquiry into allegations of hundreds of cases of child abuse in care homes in former county council areas of Clwyd and Gwynedd between 1974 and 1990.

The tribunal, led by Sir Ronald Waterhouse, heard evidence from more than 650 people who had been in care from 1974 and took almost three years to publish its report.

Counsel for the inquiry mentioned the existence of a shadowy figure of high public standing, but said that there was no substantial evidence to support the allegations.

An investigation by BBC reporter Angus Stickler at the time of the report's publication revealed allegations of a much wider circle of abuse than that uncovered by the inquiry.

One particular night that I always recall is when I was basically raped, tied down, and abused by nine different men Steve Messham, Abuse survivor

He uncovered allegations of widespread physical and sexual abuse of children not just by care system staff, but that children were being lent to paedophiles from all walks of life including businessmen, police, and a senior public figure in a paedophile ring stretching beyond the borders of north Wales, to Chester, London, Brighton and beyond.

One of the victims that Angus Stickler spoke to in 2000 was Mr Messham, who described some of the abuse he suffered. Now, reporting for BBC Newsnight and the Bureau of Investigative Journalism, he has re-interviewed Mr Messham.

"In the home it was the standard abuse which was violent and sexual. Outside it was like you were sold, we were taken to the Crest Hotel in Wrexham, mainly on Sunday nights, where they would rent rooms," Mr Messham recalled in this latest interview.

"One particular night that I always recall is when I was basically raped, tied down, and abused by nine different men."

He also stood by his claims then that his abusers included a leading Tory politician of the Thatcher era.

"You were taken by car, where basically you were sexually abused. Various things would happen, drink would be involved, it was basically rape. But it wasn't just him, there be other people involved as well," he said.

When asked how many times he was abused by the politician Mr Messham said:

"Off my head I couldn't give an exact number as it goes back many years but certainly more than a dozen."

Faxed photograph

In his new interview, Mr Messham also said that he had gone to the police in the late 1970s to report the abuse, but that he was not believed:

"I was called a liar. I was pinned up against a wall. I could still name to this day the police officer who had done it," he said.

"The police denied it and when they looked back, they finally admitted in the inquiry [that] statements were made. That's all they would say. They wouldn't say who was named in them. But they did admit I did make a statement of sexual abuse."

Mr Messham also insisted that his statements to the police included allegations of sexual abuse against the politician.

In his original investigation Angus Stickler also spoke to another victim who claimed to have been abused by the politician, as well as others.

At that time... the idea that senior public figures; politicians; celebrities could be involved in child abuse was seen as a bit far-fetched Richard Scorer, Solicitor for victims

Newsnight/the Bureau of Investigative Journalism has been unable to track him down for this latest report. However, in 2000 he described how as a teenager he was abused by the politician:

"We went out for something to eat and he pulled over in a layby and then, hey presto, oral sex took place," the man - who wanted to remain anonymous - said.

He told Angus Stickler that at the time, in the early 1990s, he went to North Wales Police to report the abuse, showing them faxed photographs of the senior Tory politician.

However, he said that the two police officers he showed the photograph to dismissed his claims, saying that since the pictures were faxed they were not sufficiently reliable evidence and no further action was taken.

The Waterhouse inquiry, which cost £12m to stage, promised to leave no stone unturned in its endeavour to uncover abuse.

However, there have been complaints that the terms of reference were too narrow, restricting investigations to abuse taking place within the care system, not beyond it.

"I don't understand why on Earth we had an inquiry when we had to leave out 30% of the abusers," Mr Messham said in his latest interview.

"And basically I was told to do that. I was told I couldn't go into detail about these people, I couldn't name them and they wouldn't question me on them."

Mr Messham says he wants a new investigation into what happened:

"I would like a meeting now with David Cameron. He's made a statement, a sweeping statement that abused people need to be believed, we haven't been believed, we've been swept under the carpet.

"It's time he knew the truth. It's time a full investigation took place and until I can meet with him and get some reassurance I don't believe we will get anywhere."

Richard Scorer, a solicitor with Pannone and Partners, who represented 30 victims at the Waterhouse inquiry, believes the original remit of the inquiry and attitudes at the time were at the heart of the problem:

"The terms of reference were an important restriction. It's also fair to say at that time, and we're going back to the mid to late 1990s here, at that time the idea that senior public figures; politicians; celebrities could be involved in child abuse was seen as a bit far-fetched," he told Newsnight/the Bureau of Investigative Journalism.

"We now know of course from recent revelations that it isn't far-fetched at all - and that's part of the reason why it's important that these allegations are looked at again," he added.

Anyone with information into these allegations - or who needs support on the issues raised in this article - can call the NSPCC on 0808 800 5000 or email help@nspcc.org.uk, or call their local police station by dialling 101.