In his interview, Mr McCann revealed how he and his wife are contemplating life in the future with their daughter still missing.

Having another child

Madeleine and her younger brother and sister were born by IVF after her parents tried for children for five years.

Asked whether they would ever have more children, Mr McCann said: "We're looking day to day at the minute.

"Even if we decided it might be good to have another child, even if we thought like that, it's a lot more complicated given our history - the fact we've had IVF with the other children and we're getting older and the chances of success go down.

"It's more complex and we wouldn't rush into anything. We haven't had any discussions. Kate has said you could never replace Madeleine and that's absolutely true."

Going home

The McCanns have not yet decided to return home to Britain but their minds are turning towards it. Mr McCann, who is on unpaid leave from his job as a consultant cardiologist at the Glenfield Hospital in Leicester, said: "Our life will never be the same. But it's been a long time now, it's three and a half months. At some point we have to say, 'OK, what is the best thing for us and the twins?'

"I have started thinking about work. I don't think it will be an immediate decision. But yes, I do see myself going back to work at some point, and it will probably be in a graded fashion.

"There's no doubt I need to be active. We have tried to influence things in a positive way and we are very busy. It is when we stop and dwell and look back, that is the hardest thing."

He added: "I think Kate's job is going to be harder because as a GP she comes face-toface with patients more. We haven't really talked about it and planned that far ahead."

Is Madeleine still alive?

Mr McCann explained why he and his wife firmly believe their missing four-year-old could still be alive. He said: "There is no logic that says we can't find Madeleine.

"Honestly, I'm not deluded. Logic is when you've got clear evidence that you can't find her.

"I think some people think we are deluded - that she is dead. Well, there is no strong evidence of that, it's scenarios, possibilities, theories.

"We've talked about it. Of course we know she might be dead. But that probability doesn't help."

Being famous

Asked if they feel they are a celebrity couple, Mr McCann replied: "We are famous. There's no disputing that. We have become famous and we never wanted that.

"We have tried recently to take ourselves back from the public eye as much as possible while still doing some campaigning but the story goes on.

"As the parents of a missing girl unfortunately there is a lot of attention on us, particularly until Madeleine is found. Let's be realistic, we can't control that. We have not chosen that path and we are certainly not celebrities. Fame is different from celebrity.

"I have seen us on the covers of magazines, of Hello!, and it is very odd to see yourself there. You think, 'Why are we on that?'"

Public perceptions

Asked what he thought the public thinks of them, Mr McCann said: "What we've been told, and our own personal experiences, is that there is huge, overwhelming support for us as parents and for what we have decided to do.

"It's hard right at the minute but we are trying not to be deflected off course. Madeleine is still missing.

"We are not going to give up on our daughter. All parents empathise with that.

"Certainly we feel supported with the messages we get through the website and the number of letters are back up to levels there were at the beginning."