KEY witnesses in and around the Ocean Club resort complex when Madeleine McCann disappeared should be asked to take part in a re‑enactment to help the Scotland Yard hunt for the child.

Former Yard Commander Dai 'Davies believes a controversial reconstruction with Kate and Gerry McCann, their holiday friends and others could be vital in encouraging new witnesses to come forward.

When top Portuguese detective Paulo Rebelo took over the case he was frustrated at not being able to stage a reconstruction as he believed it could provide a breakthrough.

However, at that time there were strains in the relationship with the McCanns, the so-called Tapas Seven and Portuguese police and there was suspicion about the motives of such an exercise.

Mr Davies, head of royal protection at the Yard and now a respected 'security consultant, said: 'I believe a reconstruction should be one of the ideas on the table and it should be seriously considered, although it would obviously have to be handled very gently and diplomatically.

'Reconstructions screened on Crimewatch many, many years after serious crimes have been crucial in solving complex and difficult inquiries. If the reconstruction was screened across Europe it may inspire someone to come forward with crucial information.'

Jane Tanner, the friend of the McCanns who claimed she saw a man carrying a child near apartment 5a of the complex at Praia da Luz on Portugal's Algarve on May 3, 2007, days before Madeleine's fourth birthday, has already taken part in a partial reconstruction for a TV 'documentary.

Another crucial witness is Irishman Martin Smith, who also saw a man carrying a child in his arms later in the evening.

Mr Davies said: 'As well as these important witnesses it would be useful to seek the cooperation of others who were working at the tapas bar.

'With the close involvement of the Yard and cooperation with all the important witnesses and an agreement for a filmed version to be screened on Crimewatch and its 'Portuguese equivalent, I believe a reconstruction would be very useful. I also think the Yard should conduct a 'thorough overhaul of all the forensic evidence as something may have been missed and they should trawl over the crucial witnesses to see if a line of inquiry was not pursued.

'A lot of photofits have been 'produced over the years and the team will be anxious to try to identify those people.' John O'Connor, former head of the Yard's Flying Squad, said: 'They are lucky in that there is already a mountain of evidence to go through and analyse and they are very good at that. They are very good at concentrating on the really important leads and how they were pursued.'

Although the Portuguese police publicly released scores of files on the case, they withheld documents with details of British people living in the area with criminal records for sex offences.

That information will now come under the microscope of the Yard's elite Homicide and Serious Crime Command unit.

Det Chief Insp Andy Redwood will lead the team and he will be reporting to Det Chief Supt Hamish Campbell, Operational Command Unit commander. The senior officer in overall charge is 'Commander Simon Foy.

Mr Campbell is used to handling difficult, high profile cases as he was responsible for investigating the 'murder of BBC news presenter Jill Dando and is known for his attention to detail and his tenacity.

It is expected DCI Redwood will at times have 10 officers working for him and he will split them up into groups concentrating on different aspects of the case.

He is expected to travel to Portugal later in the month with a small team to liaise with 'detectives in Lisbon and Portimao, some 20 miles from Luz. Portuguese police are still the lead force in the investigation.

In her book, Madeleine, published last week, Kate McCann, 43, revealed the existence of a note in the Ocean Club staff message book saying that the families were leaving their 'children behind each night.

She said: 'I was dismayed. This was a glaring light to a child taker and yet no mention is made of it in the files until December 2007. December 2007! Seven months after Madeleine's abduction! I could only conclude that its relevance had not been appreciated by the police.'

One avenue the officers will explore is whether sightings of Madeleine were taken seriously and properly examined. Last week an elderly woman contacted the Sunday Express to say she saw Madeleine at the Spanish coastal town of Torrevieja, near Murcia, the day after the kidnapping.

The woman, aged 81, said she and her husband saw a girl with a suspicious looking man near some shops. She said: 'It was definitely Madeleine because I recognised the mark in her eye. I went to the police there and I have been to British police but I don't believe the sighting was properly investigated.'

We have passed on details of this incident to private investigators 'working for the McCanns.

Last week we revealed that 'German youth worker Martin N, who is being questioned about a spate of child murders across Europe, will be asked if he was in Praia da Luz when Madeleine vanished.

German police say he has 'confessed to one child murder and will be questioned about some 40 sex attacks.