The couple and their friends all left their children in their apartments at exactly the same time for the last four nights of their holiday, according to the new witness.
A staff member at the resort where the nine-strong group enjoyed two or three-hour meals - typically washed down with eight to ten bottles of wine a night - said the nightly routine was 'set in stone'.
He said the group made a 'special arrangement' to book the same table at 8pm every night so they could sit outside, 50 metres from where their children lay sleeping. He told how the arrangement was widely known about by workers at the restaurant, who thought it was strange that other holiday-makers had to queue for reservations at the popular tapas bar. But he said he only realised after Madeleine's disappearance that the routine could have made all eight of the group's children vulnerable to a potential abductor.
He then added "The apartments are all quite close to the pool, but there are trees in between so you can't see them from the restaurant. Even though they were checking their children every 20 minutes or so there was still a lot of time they were left alone when someone could have gone in and taken them. When you think back now, because the routine was so set in stone every night, if somebody had been watching the group they would definitely have been able to work out what was going on and choose the right moment to take the child.
His eyewitness account of the group's behaviour is the first time anyone from inside the tapas bar has spoken publicly about the events of May 3. He has been interviewed by police for a total of four hours during two interviews about that night, and other evenings when the so-called 'Tapas Nine' dined at the restaurant. And his wife has also been quizzed about the first two nights of the group's holiday, when she worked at the Ocean Club's other restaurant, the Millennium.
He said: "Right from the start it was obvious the police were taking the situation very seriously and believed Madeleine had been abducted. I told them what I knew and said I wondered why they hadn't paid a babysitter. Once I realised what had happened it struck me that the arrangement had been pretty strange.
The staff member, told of the dramatic moments after Mrs McCann found that Madeleine was missing. He said the McCanns dined with their friends, David and Fiona Payne, Mrs Payne's mother Dianne Webster, Matthew and Rachael Oldfield and Russell O'Brien and his partner Jane Tanner as usual, and drank their normal eight to ten bottles of wine.
He also said: "The night of May 3 had been just a normal night. Then it all became madness. We were beginning to wind down at the restaurant and I had been clearing some tables. I went into the kitchen for a few minutes and when I came out I saw that the McCanns' table was totally empty except for the older woman. I think she was a mother of one of the friends. She looked scared.Then I heard all the shouting and screaming coming from the apartments, and my colleague told me a child had gone missing. After that it was chaos. People were running around the resort shouting for Madeleine, and we all started to help looking for her. I've never seen anything like it."
The latest eyewitness detail about the night of Madeleine's disappearance came as a team of Portuguese detectives prepared to fly to England to reinterview some of the Tapas Nine.