A London-born boy has become the first millennial saint, in a ceremony steeped in an ancient ritual presided over by Pope Leo on Sunday.

In his short life, Carlo Acutis created websites documenting 'miracles' as a means of spreading Catholic teaching, leading some to nickname him God's influencer.

His canonisation had been due in late April, but was postponed following the death of Pope Francis.

More than a million people are estimated to have made a pilgrimage to the Italian hilltop town of Assisi where Carlo's body lies, preserved in wax.

But there is another pilgrimage site associated with Carlo Acutis that has seen an increase in visitors since it was announced that he was to be made a saint - Our Lady of Dolours Church in London.

The font at the back of the Roman Catholic church in the Chelsea area was where Carlo was baptised as a baby in 1991.

To the side of the church, an old confession booth has been converted into a shrine to him. In it, a relic holder contains a single strand of Carlo's hair.

His family were in finance and were working temporarily in London. Although they didn't use the church much, they decided to come and ask to have the child baptised. So Carlo was a flash, a very big flash in the life of the parish community, says Father Paul Addison, a friar at the church.

Carlo was not yet six months old when his parents moved back to their home country of Italy, and he spent the rest of his life in Milan. There, he was known for a love of technology and is said to have enjoyed playing video games.

While some who knew Carlo Acutis say he did not appear to be especially devout, as a teenager he created a website documenting miracles, with pages now framed at the church in Chelsea.

But he died of leukemia at just 15.

Following Carlo's death, his mother, Antonia Salzano, dedicated years advocating for his canonization. This involved proving that he had performed miracles, one of which occurred on the day of his funeral, when a woman with breast cancer reportedly prayed for Carlo and found her cancer had disappeared completely.

Pope Francis attributed two miracles to Carlo Acutis, and he was due to be canonized on April 27. However, the ceremony had to be postponed due to the Pope's death.

Many of those who had traveled to Rome for the canonization found themselves at Pope Francis's funeral instead. Diego Sarkissian, a young Catholic from London, expressed excitement for Carlo's canonization, noting, The fact that you can think of a saint doing the same things as you, wearing jeans, feels so much closer than what other saints have felt like in the past.

This canonization is a significant effort by the Catholic Church to resonate with younger generations, hoping to inspire faith amidst contemporary cultural values.