David Cameron has accepted his first job since quitting as Prime Minister following the Brexit vote.
The 50-year-old, who resigned in June after six years in Number 10, has taken an unpaid role at the National Citizens Service Trust.
The charity implements his flagship Big Society policy, helping 15 to 17-year-olds take part in volunteering and social development bootcamps.
Writing in The Daily Telegraph, Mr Cameron said: "When I look back over six years as Prime Minister, one of my proudest achievements is the creation of National Citizen Service.
"I often get stopped in the street by parents who tell me what a difference NCS has made in the lives of their children; and I regularly receive letters from young people who have so enjoyed taking part.
"From the pilot projects that I began as Leader of the Opposition to the full-scale programme that we have today, more than 275,000 people have taken part in what has become the fastest-growing youth movement of its kind in the world."
Mr Cameron is set to become the chairman of the charity's patrons board, which will oversee expansion plans.
He added: "I am delighted that my first role in my life after politics is to continue my association with this fantastic programme by becoming chairman of NCS Patrons, bringing together a senior cross-party and cross-sector group of patrons and ambassadors who can help NCS to reach more youngsters."