The McCanns are under investigation from British police and social services to assess whether their twin son and daughter are at risk.

Given the gravity of the allegations facing the McCanns, social services have no choice but to examine any possible risk to young children who have endured four months in the glare of the media spotlight.

 

The couple awoke yesterday after their first night back in the village of Rothley since they flew home on Sunday without Madeleine.

When they realised, last Thursday, that Mrs McCann was to be made an official suspect in the disappearance of her daughter, they vowed to remain in Portugal to clear her name. However, during 13 hours of interrogation, Portuguese detectives threatened her with the terrible ultimatum of confessing - or losing her twins.

Officers said they would charge both her and her husband in connection with the case, and claimed that bail would be denied while they awaited trial.

This would have resulted in the twins perhaps being taken into care by Portuguese social services for at least a year.

Hurriedly, the McCanns arranged to return to Britain - only to find that Leicestershire police were discussing them social workers.

John Coughlan, Joint President of the Association of Directors of Children's Services, explained: "In cases such as this, social workers working for the host authority need to make a sober assessment of the facts in the case.

"At the meeting they would try to establish what they know and what they don't - and would use that to try and determine whether there is any real risk to the children.

"If they decide that there is a risk, they would then consider what they are going to do about it, step by step."

He added: "In most cases, social service workers do not come crashing down the drive and snatch the children. They are much more likely to take a more measured approach."

Technically, if social workers conclude that there is a real risk to the twins, they could move to take the two children away from their 39-year-old parents.

In this case, the Leicestershire social workers are unlikely to have a great deal of reliable information about the McCanns' behaviour.

As the Portuguese police force would not hand over information that may be used in a criminal prosecution, the British social workers may therefore decide to carry out an initial interview with the McCanns before taking further action.

Nevertheless, Mr McCann's sister Philomena revealed that the family are preparing for the worst.

 

She said: "Madeleine's godmother is down at Rothley right now and she is prepared to step into the breach if Gerry and Kate are asked to return to Portugal.

"The family are more than willing to look after the children and they will not become wards of the state here or anywhere else."

Yesterday the McCanns were visited at their large modern home by a police "crime reduction officer" who explained that he gives information about "personal safety".

The visit raised fears that the couple could be targeted by members of the public who believe they are responsible for Madeleine's death.

Back in Portugal, a police source said phone calls to and from the couple form "a major strand" of the inquiry.

For more than a month, the couple have been under round-the-clock surveillance, with their calls recorded and their e-mails intercepted by the Portuguese police.

Now it is alleged that something said on the phone has added to detectives' conviction that Madeleine died the night she went missing.

The Mail has discovered new details about the conclusions drawn by the British scientists.

Portuguese police believe the crucial forensics supports their case that some terrible harm came to Madeleine in the apartment.

A source in the UK said last night the results of toxicology tests were "significant", indicating that police are focusing on some sort of medication or poison in the apartment.

The McCanns have repeatedly denied accidentally overdosing their daughter on sedatives to help her sleep while they went out to dinner.