Her picture featured on a huge projected poster along with two other missing children, Javian Matthews, 14, from London and Samantha Osborn, 15, from Buckinghamshire who both disappeared in April this year.

The Marble Arch landmark was bathed in a pink light dotted with yellow letters heralding the relaunch of the National Missing Persons Helpline.

The charity has been renamed as Missing People, and Madeleine's uncle John McCann is to visit staff and volunteers at the organisation's headquarters in central London later today.

Missing People will also announce a new campaign to adopt a yellow ribbon as an official symbol to remember anyone who has disappeared.

Chief Executive of Missing People Paul Tuohy said: "Madeleine's disappearance has been a wake-up call that 'missing' is a social issue.

"Our charity offers support to around 2000 families each year and directly as a result of our work we find 10 missing people every week.

"We are here for all missing people and although only three could be highlighted tonight, our work goes on for many, many more."