The parents of Madeleine McCann today thanked the millions of people who have helped in the search for their daughter, as a huge inflatable billboard with the abducted girl’s face on it was launched in Portugal.

Kate and Gerry McCann walked to the beach at Praia da Luz at lunchtime to visit the poster, which had been put up by two men from Glasgow to help publicise the hunt for Madeleine, who was abducted from the bed of their Algarve holiday apartment 25 days ago.

Chris Lennox, 35, and Les Harley, 51, had driven down from Scotland to the Algarve with the 800 sq ft poster within an inflatable frame.

Mr McCann, a consultant cardiologist, said: “We have thanked everyone on several occasions. Some people are going to extraordinary lengths to help.

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”We would like to thank the thousands, if not millions, of people who are doing little things in their own way, in making donations to the fund or distributing posters on holiday.

”Anything that people do to raise awareness of Madeleine’s disappearance, we thank them from the bottom of our hearts.

”We believe this will make a difference in the search for Madeleine.”

Mr and Mrs McCann were today finalising plans for a visit to the Vatican on Wednesday during which they hope to have an audience with the Pope before he leads prayers in St Peter’s Square during which Madeleine is expected to be mentioned.

Mrs McCann, wearing a brown skirt, white top and clutching her daughter’s Cuddle Cat gazed at the huge poster of Madeleine.

The couple held hands as they thanked Mr Lennox and Mr Harley for their hard work. Mr McCann described the billboard as “brilliant”. Mr Lennox, 35, from Prestwick said he had a young family and felt he wanted to do something to help.

“My heartstrings have been pulled on this and I want to help. I have a family with small kids and my wife has been following this from day one.

“She told me to come out here and do what I could. I am clearly here to help raise awareness.” Mr Harley, from Irvin in Ayrshire added: “I am a family man, I have children and grandchildren.

“When I was given the opportunity to come down here I just jumped at the chance. The rest of the world has been watching this.”

The two men, who work in advertising, intend to take the poster around the Algarve and set it up in prominent places to remind people of Madeleine. Above the two large pictures of the little girl, there is the £1.5 million reward and numbers to contact if anyone has any information. The two men left the UK on Friday night and drove 2,200 miles to reach Portugal.

The Pope has been following the reports of Madeleine’s disappearance and about how the McCanns have drawn on their Catholic faith since the abduction.

The couple have said that the visit to the Vatican, scheduled for Wednesday, would help them spiritually. Mr and Mrs McCann will also visit Madrid and Seville before moving on to Berlin and Amsterdam.

The cities have been selected because they are in countries that have large numbers of tourists. The McCanns hope to meet David Beckham in Madrid, to thank him for helping to promote the appeal to find their daughter.

They are also thought to be considering visiting Morocco, after reports that a girl matching Madeleine’s description had been seen in Marrakech, and they have been invited to Greece and the United States.

Mr and Mrs McCann hope that, in each country they visit, they can meet the government minister in charge of child welfare and a local charity involved in protecting children. They plan to give an interview to each state broadcaster.

The couple have been offered the use of a private jet by Sir Philip Green, the billionaire owner of BHS and Topshop. A child psychologist will visit the family this week to help to explain to the twins what has happened to Madeleine.

The Prince of Wales and the Duchess of Cornwall yesterday expressed their “deep concern” and sympathy.

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