It’s a scandal that’s dogged the Home Office for years. Now the Prime Minister has taken centre stage in the row over the fate of radical Islamist cleric Abu Qatada.

Home Secretary Theresa May has been accused failing to check the deadline for appeals to the European Court of Human Rights – a blunder that could extend Qatada’s stay in Britain.

Now Mr Cameron has defended her, insisting in a radio interview that government officials had checked the situation and received assurances from the Strasbourg court.

FactCheck navigates the twists and turns of a case that could prove to be one of the coalition’s biggest embarrassments.

Who is Abu Qatada?

The Jordanian cleric has been described as a leading extremist and al-Qaeda associate, although he has never been convicted of a crime in the UK.

Qatada was first jailed under anti-terror laws in 2002 while living as in London as an asylum seeker. The authorities regard him as a security threat and want to deport him to Jordan.

Why is he still in Britain?

Qatada has been released on bailed then re-arrested three times over the years while attempting to fight extradition on human rights grounds.

The latest ruling, on January 17 this year (remember that date), saw the European Court of Human Rights agree that he can be deported to Jordan, but only if the authorities there give diplomatic assurances that he will get a fair trial.

On April 17 – last Tuesday – he was arrested yet again, with much fanfare. Mrs May said she had received assurances from the Jordanian government so deportation proceedings could begin.

And because a three month period for appeals had passed, his lawyers could not now contest the ECHR’s January ruling. Or so the government thought.

But on the night of his arrest, Qatada did launch an appeal. The government says it’s too late, as the three-month deadline was midnight on Monday April 16. The preacher’s legal team begs to differ.

Who’s right?

That’s for a panel of judges at the court to decide. If they rule that Qatada’s appeal was inside the deadline, the appeal could be considered by the court’s Grand Chamber, spelling lengthy delays, and acute embarrassment for the government.

The Home Office say there was never any doubt in their minds that the appeal should have lapsed at midnight on Monday, as there was a clear precedent.

FactCheck has seen one document that suggests that, in a previous case, the court made an initial judgement on February 22 and the decision became final on November 22, because the three-month appeal period lapsed on that day.

So there was some justification for Home Office lawyers to think the same principle would apply in the Qatada case – meaning an appeal on Tuesday 17 would have been too late.

On the other hand, the Home Office haven’t shown us anything that spells out the exact position in black and white, which means it would have been sensible to have sought expert legal advice or contacted the court for clarification.

A number of legal experts have said Mrs May is in the wrong, including Professor Philip Leach from London Metropolitan University, the barrister and former government lawyer Carl Gardner, and Nathalie Chene from the Council of Europe’s legal department.

Did the Home Office check?

Mrs May dodged that specific question while answering questions in the Commons on Thursday last week. Despite a string of questions from the opposition, the Home Secretary refused to say whether she had sought specific assurances from the court or whether officials had told her if there was some doubt over the dates.

But speaking on BBC Radio this morning, Mr Cameron insisted that the Home Office had checked with the court and received assurances about the deadline.

In the interview, handily transcribed by the Telegraph, Mr Cameron said what Mrs May refused to spell out a few days previously in parliament.

Did the Home Office ask the court when the deadline was? “Yes,” Mr Cameron replied.

And was there an answer? “Yes. Absolutely.”

He went on: “The Home Office believed, and checked during the process, that the date expired on Monday night…They were told throughout that the deadline expired on the Monday night.”

Why had Mrs May been so careful to avoid answering those direct questions if the answers were as simple as that?

We asked the Home Office if they had some documentary evidence to back up the Prime Minister’s position – some emails or written correspondence that would stand up the “we checked” story.

They said they had no plans to publish anything of that nature.

The European Court of Human Rights has also failed to confirm or deny whether they really did have a conversation with the Home Office about time limits.

The Prime Minister’s official spokesman later added: “My understanding is that the Home Office had conversations with officials at the European Court and the purpose of those conversations was to check our view.”

If those were telephone conversations, and they were not recorded or transcribed, we will never know for sure what was said.

Where is Qatada now?

The man in the eye of the storm is still cooling his heels, having been refused bail by the Special Immigration Appeals Commission. But the judge, Mr Justice Mitting, has said he would reconsider bail if deportation “is not imminent”.

If the ECHR allows Qatada’s appeal to go ahead, it won’t be imminent, so we could see the cleric out of jail within months, although he’s likely to be under strict conditions.

By Patrick Worrall