Ms Pepinster, whose book The Keys and The Kingdom: Britain and the Papacy from John Paul II to Francis is published next month, said: “Cardinal Cormac Murphy-O’Connor was a popular, genial man but beneath his jovial exterior was someone of great canniness who knew exactly how the Vatican worked.

“And that canniness meant he ensured his friend was elected Pope Francis - a pope who has made a huge impact on the Catholic Church and the world. There have been kingmakers in history; Cormac Murphy-O’Connor turned out to be a popemaker.”

Pope Francis was elected on March 13 2013, the second day of the conclave, on the fifth ballot. He need two-thirds of the 115 votes to win. It is thought the votes delivered by Murphy-O’Connor were instrumental. The two men became close friends after meeting for the first time when they were made cardinals on the same day by Pope John Paul II.

In 2013, Murphy-O’Connor was too old to vote under Vatican rules, but he travelled to Rome, like many other elderly non-voting cardinals, to participate in talks, called congregations, before the conclave.

Shortly after his elevation, Pope Francis was overheard telling Murphy-O’Connor: “Tuo e colpevole”, translated as “you’re to blame”.