The couple disclosed that they almost decided against going to a tapas restaurant opposite their apartment in Praia da Luz on May 3 last year.

But they decided against a plan to take the children to another restaurant because of the distance, they revealed.

In a documentary to be screened tonight on ITV1, Mrs McCann also spoke of how she had “persecuted” herself for a year for not paying more attention to a remark by Madeleine on the morning before her disappearance that she had been crying the previous night in her parents’ absence.

Interviewed for the programme, Madeleine, One Year On: Campaign For Change, the McCanns also spoke extensively of their emotions on the night of May 3/4 and their desperate dawn search through deserted streets for their daughter.

They also described their feelings on being made “arguidos”, or official suspects, in the case by Portuguese police as like being “in the middle of a horror movie”.

In the two-hour documentary, which charts their campaign for an EU-wide missing child alert system, Mr McCann spoke of their current existence with no news of Madeleine’s whereabouts as like “purgatory”.

Breaking down in tears repeatedly, Mrs McCann spoke extensively about her experiences and hopes for the future.

Programme-makers insisted the couple had no editorial control and had not been paid, although a £10,000 donation was made to the Find Madeleine Fund.

Producer Emma Loach, who spent months working with the couple and conducted the interviews, said she had been moved by the McCanns’ situation.

“As parents we could all be in that position,” she said.

“I’ve got three boys a similar age. They made a judgment call that went terribly wrong for them. I feel I make similar judgment calls every single day.”

In the programme, Mrs McCann hinted openly for the first time at a deal reportedly offered to her by police if she admitted accidentally killing Madeleine and staging an abduction. She told the programme she was not going to be “railroaded”.

The couple admitted they were effectively forced to leave Portugal two days after being declared arguidos last September because they felt it was no longer “safe” for them.

Mrs McCann also attacked Portuguese police and openly accused them for the first time of leaking details of the investigation to smear them.

The couple spoke about their emotions on going home four months after Madeleine’s disappearance but without her. They also described some of the hate mail they have received. At one point Mr McCann read out a Christmas card which called them “f****** thieving bastards” adding: “Your brat is dead because of your drunken arrogance.”

Repeating her belief that Madeleine could still be alive, Mrs McCann also spoke movingly of seeing their daughter’s best friend and wondering whether she, too, would be taller now or writing her name.

But at one point she also contemplated “the thought of living like this for another 40 years”.

Mrs McCann spoke of her relationship with her daughter whom she called a “buddy”.

She also described her need to protect her two other children, twins Sean and Amelie, on hearing she was to be made an arguido, as like a lioness protecting her cubs.

Speaking about May 3 in detail, Mr McCann said the couple and their seven friends considered going out to eat at the Millennium, another restaurant, rather than having tapas nearby and leaving their children sleeping.

“I think the worst thing is we kind of almost thought about not going and . . . did,” he said.

Mrs McCann added: “In fact, we were all . . . going to go up to the Millennium again, that was with the kids, which is what we did the first night. It was just because the walk was so long and we didn’t have a buggy and the kids were tired by that time.”

Mrs McCann spoke openly about Madeleine’s comments on the morning of May 3.

She told the interviewer: “I can’t remember if we’d just had breakfast. It was sort of fairly early in the morning.

“She just very casually really said, Where were you last night when me and Sean cried?’ “And we immediately looked and said, you know when was this Madeleine, was this when you were going to sleep?’ and she didn’t answer.

“And then she just carried on playing, totally undistressed.”

Emphasising that the couple had taken Madeleine’s comment as simply a passing remark, Mrs McCann went on: “We obviously told the police because we thought does that indicate that someone’s been round the night before and that’s what’s woken her up?’ which is significant.

“You know, I’ve persecuted myself over and over again about that statement because you think: why didn’t I kind of just hold her and say, What do you mean? What do you mean?’”