Gazing at the camera with his hair neatly parted, tie tightened up to his collar and a twinkle in his eye, the boy looked every inch a clean-cut Catholic school student.

To his friends, Robert Prevost – or Bob, as they called him – was a “trickster” who loved to play pranks on his classmates under the watchful eyes of the nuns. Now, to the rest of the world, he is Pope Leo XIV.

“What a jokester he was,” one former student told The Telegraph, while another recalled him playfully poking them in the back of the head with a pencil.

On Thursday, former classmates saw him go from a clever young boy playing pranks at the back of the room to a man with the eyes of the world upon him, emerging on the balcony of St Peter’s Basilica to greet the crowds below.

Leo’s unlikely ascent to become the first American Pope began here, on the South Side of Chicago.

Born in 1955, he has Spanish, French and Italian ancestry, and is descended from New Orleans’ Creole population. He attended St Mary of the Assumption School in Dolton, a suburb of Chicago, and later earned a maths degree at Villanova University in Pennsylvania.