Archbishop of Canterbury's meeting with Pope Leo will be a moment for the history books

ITV News Presenter Julie Etchingham speaks exclusively with Dame Sarah Mullally, the new Archbishop of Canterbury about her upcoming visit on Monday

It will be a moment for the history books.

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.

Subscribe free to our weekly newsletter for exclusive and original coverage from ITV News. Direct to your inbox every Friday morning.

But the trip will inevitably highlight too, the deep division between the two on some issue - not least the ordination of women. The Roman Catholic Church recently ruled women could not even be permitted to be deacons.

The Archbishop’s visit marks the anniversary of a moment of history too.

It’s 66 years since the first meeting between an Archbishop of Canterbury and the Pope.That meeting in Rome was the first time leaders of the Anglican and Roman Catholic Churches had come together since the Reformation in 1534, when Henry VIII declared himself head of the English Church in place of the Pope.Six years later another meeting hugely significant for Anglican-Roman Catholic relations took place.

The meeting between Pope Paul VI and Archbishop Michael Ramsay took place in the Sistine Chapel.

A Common Declaration was issued by the pair - despite fierce opposition by many Anglicans and Protestants - including Northern Ireland MP and firebrand religious leader, Ian Paisley, who saw it as an act of treachery.

The Declaration was a clear signal of trajectory, committing the Roman Catholic Church and the Anglican Communion towards unity.

In a moment of deep emotion, Pope Paul VI later gave Archbishop Ramsay his Episcopal ring and ever since, Archbishops of Canterbury have worn this ring whenever they visit Rome, seeing it as a symbol of the Anglican Communion's commitment to reconciliation and ecumenical ties with the Roman Catholic Church.

Archbishop Mullally wore the ring, made of a large square green stone divided by gold cross and studded with four diamonds, at her installation last month. She will wear it again tomorrow when she meets Pope Leo.

It had to be specially re-sized to fit her finger.

Since that first common declaration six decades ago, a number have been issued; all focusing on unity and shared aspects of common faith. And while there have been obstacles around Communion and the ordination of women which remain unresolved, there has always been a desire for Christian unity.

Pope Leo has, like his predecessor Pope Francis, indicated he is open to giving women more senior and leadership roles within the church. And for many progressive Roman Catholics, Archbishop Sarah will be a symbol of inspiration and hope.

Even though divisions remain on theological issues, there is great respect and warmth between these two new leaders.

Catholic Cardinals attended the Archbishop’s installation at Canterbury Cathedral last month and Pope Leo wrote to her personally.

“We know that the ecumenical journey has not always been smooth. Despite much progress, our immediate predecessors, Pope Francis and Archbishop Justin Welby, acknowledged frankly that 'new circumstances have presented new disagreements among us'.

"Nevertheless, we have continued to walk together, because differences cannot prevent us from recognising one another as brothers and sisters in Christ."

The pair have already seized an opportunity of unity in speaking out in one regard in particular: President Trump.

The American Pope and the American president have been at loggerheads in recent weeks over the war in Iran.

On his recent tour of Africa, Pope Leo spoke of the world being "ravaged by a handful of tyrants".

On the same day, Archbishop Sarah issued a statement in solidarity with "her brother Pope Leo XIV", urging Anglicans to "join with his Holiness in raising our voices for peace and justice throughout the world".

So for the first time tomorrow, after all the warm missives between them, they will meet face to face. These personal moments are profoundly significant in forming the basis of a friendship and collaboration.

The Archbishop of Canterbury will first have a private audience with the Pope in the morning. She will then join him for midday prayer in the Chapel of Urban VIII within the Apostolic Palace, accompanied by the also new Roman Catholic Archbishop of Westminster, Richard Moth.

In anticipation Archbishop Sarah has said: "I give thanks for the deepening dialogue and fellowship between Anglicans and Catholics over the last sixty years. It is a joy and privilege to meet and pray with His Holiness Pope Leo XIV and I look forward to our conversation and prayer."

Of course, English is their native language which will make talking to each other much easier without the need for interpreters.

There are so many questions ahead of this historic meeting.

What will they discuss? Will they get on? How will Leo respond to a female leader of the Anglican Communion? What path for Christian unity do they foresee?

Will the pair use this first personal meeting to issue another statement about the direction in which President Trump appears to be taking the world?

How might the current vivid spotlight on Pope Leo - who has found his voice so powerfully - serve both leaders to amplify a message of peace?

We will find out tomorrow.

From Westminster to Washington DC - our political experts are across all the latest key talking points. Listen to the latest episode below...