Coo coo ca choo, Mrs Robinson

Within hours of Northern Ireland's First Minister Peter Robinson going on television this week to admit that his wife had been unfaithful to him, and that he was trying to rebuild their marriage, it transpired that the man Iris Robinson had an affair with was a teenager, 40 years her junior.

Kirk McCambley, proprietor of the Lock Keepers Inn cafe in south Belfast, was only 19 when he had the short affair with Iris Robinson 18 months ago. She was 59 at the time.

But while the revelation of his youth has got tongues wagging across Northern Ireland, a more serious aspect of the affair has been exposed by a BBC Spotlight documentary.

The Darragh MacIntyre-fronted programme alleges that Iris Robinson, who is herself a DUP MP - for Strangford, County Down - broke parliamentary rules by not declaring her interest in organising a £50,000 business deal to help her lover establish the Lock Keepers Inn cafe.

Furthermore, the programe claims that her husband became aware of the situation but did not take steps to alert the  appropriate authorities, making him a rule-breaker too.

It was after the BBC went to Robinson on Tuesday to put its claims to him directly before broadcasting the documentary that the First Minister made the decision to go on television and admit to his wife's affair. In an emotional broadcast on Wednesday, he revealed that Iris had tried to take her own life after admitting to the affair. He did not explain that the 'other man' was 19-year-old McCambley.

Today, there were calls from opposition MPs in Ulster for Mrs Robinson to stand down immediately as an MP, even though she has already stated that she plans to leave politics at the next election.

Sir Reg Empey, the UUP leader, said it was clear to him Mrs Robinson's position was "utterly untenable" and that she should resign all her positions - she is a local councillor as well as an MP - with immediate effect.

In the wake of her husband's TV appearance, Iris Robinson issued a statement admitting both the affair and her suicide attempt. "Everyone is paying a heavy price for my actions... I am so, so sorry," she said.

Until now, Iris Robinson was best known for another hugely controversial moment in her political career - when she told a BBC radio show in 2008 that homosexuality was an "abomination" which made her feel "nauseous". She was reacting to the news of a homophobic attack on a gay man in Northern Ireland, when she suddenly spilled her private feelings.

Despite instant condemnation, she continued to defend her views, adding: "Just as a murderer can be redeemed by the blood of Christ, so can a homosexual.... If anyone takes issue, they're taking issue with the word of God." ·