When Dame Sarah Mullally, the new Archbishop of Canterbury, enters the Apostolic Palace at the Vatican on Monday, she will be following in the footsteps of her predecessors, but with one vital difference.

She will be the first woman to do it.

The mere sight of her meeting the head of the Roman Catholic Church, which unlike the Anglican Church still has an all-male priesthood, will be remarkable.

The two, who have already called one another “brother” and “sister”, will not only speak personally for the first time, but will pray together, side by side.

The visit will be a profound symbol of warmth and a shared mission for the two Churches, split so violently in the Reformation under Henry VIII.

It is highly significant that the Archbishop has chosen Rome as her first foreign trip in her new role, to stand alongside the foremost spiritual leader in the world.