Something significant happened in Rome this week when the Archbishop of Canterbury met the Pope for the second time since the two men took office, within days of one another, just over a year ago.

They have agreed a joint project to use the worldwide reach of their churches to combat the global trade in human trafficking. They discussed how to pressurise 50 top multi-national companies to render their supply chains free of forced labour by 2020 – and ensure they “slavery proof” the investments and purchasing of their own churches. There were other areas of practical co-operation, including peace-building in areas like South Sudan. As he left Rome, Archbishop Justin Welby hinted that other new initiatives had been discussed.

But what was also striking was the renewed commitment the two men made to the idea that their two churches should merge. Pope Francis said that “the goal of full unity… remains the aim which should direct our every step along the way”.

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This is a process which many assumed had stalled. The decision by the Church of England to ordain women in 1992 caused a theological rift between Canterbury and Rome. The ordination in the wider Anglican communion of openly gay bishops, like Gene Robinson in 2003, created another obstacle. And next month the General Synod is likely to vote for women bishops – something Rome sees as a greater theological problem even than female priests.

Yet in the background heavyweight theological discussions, on what unites rather than divides the two churches, have been continuing. One of the purposes of Archbishop Welby’s visit to Rome was to launch a new website (www.iarccum.org) dedicated to implementing better ecumenical relations.

Shape Created with Sketch. Pope Francis - the first year: From white smoke to selfies, a look back at 12 months in pictures Show all 40 left Created with Sketch. right Created with Sketch. Shape Created with Sketch. Pope Francis - the first year: From white smoke to selfies, a look back at 12 months in pictures 1/40 3 March 2014 Pope Francis leads his Sunday Angelus prayer in Saint Peter's square at the Vatican 2/40 9 March 2013 Days before becoming Pope. Cardinal Jorge Mario Bergoglio arrives for a pre-conclave meeting on March 9, 2013 at the Vatican. The conclave of 115 'cardinal electors' began a few days after this picture was taken, on March 12, gathering to choose the 266th pope 3/40 13 March 2013 The sign that the decision has been made. White smoke is seen from the roof of the Sistine Chapel indicating that the College of Cardinals have elected a new Pope Getty Images 4/40 13 March 2013 Facing the crowds for the first time. All eyes are on the newly elected Pope Francis I as he looks out at the thousands of people in St. Peter's Square 5/40 14 March 2013 Pope Francis leading Mass at the Sistine Chapel, a day after his election AFP/Getty Images 6/40 17 March 2013 One young pilgrim with a picture of Pope Francis Getty Images 7/40 19 March 2013 Pope Francis walks to the altar during his inauguration mass at St Peter's square 8/40 19 March 2013 In the Popemobile on St Peter's square. The Pope arrives for his grandiose inauguration mass on March 19, 2013 9/40 19 March 2013 The much loved smile. Pope Francis waves to the crowd from the papamobile during his inauguration mass at St Peter's square on March 19, 2013 at the Vatican 10/40 March 2013 Pope Francis washes the feet of a prisoner at the Casal Del Marmo Youth Detention Centre Getty Images/2013 L'Osservatore Romano 11/40 18 April 2013 Miguel Delgado Galindo presents a jersey of Argentine soccer star Lionel Messi to Pope Francis, at the Vatican AP 12/40 22 May 2013 Pope Francis in St Peter's Square Getty Images 13/40 June 2013 Pope Francis at the Vatican in June 2013 AFP/Getty Images 14/40 14 June 2013 Pope Francis welcomes the Archbishop of Canterbury Reuters 15/40 8 July 2013 The first time they let him out of Rome. Pope Francis waves excitedly to the crowds in Lampedusa during his first official trip out of Rome. 16/40 26 July 2013 Another trip in the Popemobile. Pope Francis travels in style on his way to Copacabana Beach during World Youth Day celebrations on July 26, 2013 in Rio de Janeiro, Brazil. 17/40 26 July 2013 Pope Francis delivers a speech to Catholic faithful at Copacabana beach in Rio de Janeiro AFP/Getty Images 18/40 13 August 2013 Pleased with his gift. A private audience with the Italy and Argentina Football Teams at The Vatican on August 13, 2013 19/40 21 August 2013 Pope Francis with his predecessor Pope Emeritus AP 20/40 29 August 2013 The selfie Pope Francis had taken inside St. Peter's Basilica with youths from the Italian Diocese of Piacenza and Bobbio who came to Rome for a pilgrimage, at the Vatican 21/40 7 September 2013 Pope Francis said he asked the priest for "mercy" AFP/Getty 22/40 7 November 2013 Pope Francis caresses a sick person in Saint Peter's Square EPA 23/40 20 November 2013 Blessing a disfigured man in St. Peter's Square Rex Features 24/40 December 2013 Pope Francis has been named Time magazine's Person of the Year Time 25/40 8 December 2013 In silent prayer. Pope Francis prays in front of the statue of the Immaculate Conception at Spanish Steps December 8, 2013 in Rome, Italy. The statue was consecrated in 1857, several years after the church adopted the dogma which states that Mary was conceived without the stain of original sin. Following tradition, Pope Francis celebrated the Feast of the Immaculate Conception by venerating the statue 26/40 14 December 2013 What an interesting skull cap you have there.. A child inspects Pope Francis' attire during an audience with beneficiaries and volunteers of the Santa Marta pediatric dispensary in Paul VI Audience Hall in the Vatican on December 14, 2013 27/40 December 2013 Pope Francis holds a scarf of Argentine football team San Lorenzo of which he is a fan, during his visit to the Sao Jeromino Emiliani church at the Varginha favela in Rio de Janeiro GETTY IMAGES 28/40 December 2013 Pope Francis wears his papal vestment during his inauguration mass at St Peter's square as Latin America's first pontiff GETTY IMAGES 29/40 December 2013 Pope Francis wears a Fisherman's Ring, made of gold-plated silver, symbolising the Holy Father's role as a 'fishers of men' GETTY IMAGES 30/40 January 2014 "The Times They Are A-Changing" indeed: Pope Francis waves on his Rolling Stone cover shoot 31/40 5 January 2014 A seagull flies past pope Francis as he arrives for the Angelus noon prayer he celebrates from the window of his studio overlooking St. Peter's Square at the Vatican on Sunday 5 January AP 32/40 6 January 2014 The lamb of God. The pope has a lamb put around his neck by a woman dressed as a character from the nativity scene at Church of St Alfonso Maria dei Liguori in the outskirts of Rome 33/40 13 January 2014 Pope Francis baptises one of 32 babies during a mass in the Sistine Chapel at the Vatican 34/40 14 January 2014 Pope Francis being presented with a Harley Davidson Dyna Super Glide motorcycle in Vatican 35/40 22 January 2014 Pope Francis greets the crowd as he arrives for his general audience at St Peter's square on January 22, 2014 at the Vatican AFP/Getty Images 36/40 January 2014 Pope Francis at the weekly papal audience in Rome, January 2014 Rex Features 37/40 February 2014 A close-up of Pope Francis' passport 38/40 19 February 2014 Facing some challenges. A gust of wind blows Pope Francis' mantle as he reads his speech during his weekly general audience in St. Peter's Square 39/40 26 February 2014 Pope Francis kissing a child dressed as Pope as he arrives in Saint Peter's Square to lead his Wednesday's General Audience, in Vatican City AP 40/40 5 March 2014 At work, in concentration. Pope Francis blesses the altar in the Santa Sabina church in Rome on March 5, 2014, as he celebrates the mass for Ash Wednesday, opening Lent 1/40 3 March 2014 Pope Francis leads his Sunday Angelus prayer in Saint Peter's square at the Vatican 2/40 9 March 2013 Days before becoming Pope. Cardinal Jorge Mario Bergoglio arrives for a pre-conclave meeting on March 9, 2013 at the Vatican. The conclave of 115 'cardinal electors' began a few days after this picture was taken, on March 12, gathering to choose the 266th pope 3/40 13 March 2013 The sign that the decision has been made. White smoke is seen from the roof of the Sistine Chapel indicating that the College of Cardinals have elected a new Pope Getty Images 4/40 13 March 2013 Facing the crowds for the first time. All eyes are on the newly elected Pope Francis I as he looks out at the thousands of people in St. Peter's Square 5/40 14 March 2013 Pope Francis leading Mass at the Sistine Chapel, a day after his election AFP/Getty Images 6/40 17 March 2013 One young pilgrim with a picture of Pope Francis Getty Images 7/40 19 March 2013 Pope Francis walks to the altar during his inauguration mass at St Peter's square 8/40 19 March 2013 In the Popemobile on St Peter's square. The Pope arrives for his grandiose inauguration mass on March 19, 2013 9/40 19 March 2013 The much loved smile. Pope Francis waves to the crowd from the papamobile during his inauguration mass at St Peter's square on March 19, 2013 at the Vatican 10/40 March 2013 Pope Francis washes the feet of a prisoner at the Casal Del Marmo Youth Detention Centre Getty Images/2013 L'Osservatore Romano 11/40 18 April 2013 Miguel Delgado Galindo presents a jersey of Argentine soccer star Lionel Messi to Pope Francis, at the Vatican AP 12/40 22 May 2013 Pope Francis in St Peter's Square Getty Images 13/40 June 2013 Pope Francis at the Vatican in June 2013 AFP/Getty Images 14/40 14 June 2013 Pope Francis welcomes the Archbishop of Canterbury Reuters 15/40 8 July 2013 The first time they let him out of Rome. Pope Francis waves excitedly to the crowds in Lampedusa during his first official trip out of Rome. 16/40 26 July 2013 Another trip in the Popemobile. Pope Francis travels in style on his way to Copacabana Beach during World Youth Day celebrations on July 26, 2013 in Rio de Janeiro, Brazil. 17/40 26 July 2013 Pope Francis delivers a speech to Catholic faithful at Copacabana beach in Rio de Janeiro AFP/Getty Images 18/40 13 August 2013 Pleased with his gift. A private audience with the Italy and Argentina Football Teams at The Vatican on August 13, 2013 19/40 21 August 2013 Pope Francis with his predecessor Pope Emeritus AP 20/40 29 August 2013 The selfie Pope Francis had taken inside St. Peter's Basilica with youths from the Italian Diocese of Piacenza and Bobbio who came to Rome for a pilgrimage, at the Vatican 21/40 7 September 2013 Pope Francis said he asked the priest for "mercy" AFP/Getty 22/40 7 November 2013 Pope Francis caresses a sick person in Saint Peter's Square EPA 23/40 20 November 2013 Blessing a disfigured man in St. Peter's Square Rex Features 24/40 December 2013 Pope Francis has been named Time magazine's Person of the Year Time 25/40 8 December 2013 In silent prayer. Pope Francis prays in front of the statue of the Immaculate Conception at Spanish Steps December 8, 2013 in Rome, Italy. The statue was consecrated in 1857, several years after the church adopted the dogma which states that Mary was conceived without the stain of original sin. Following tradition, Pope Francis celebrated the Feast of the Immaculate Conception by venerating the statue 26/40 14 December 2013 What an interesting skull cap you have there.. A child inspects Pope Francis' attire during an audience with beneficiaries and volunteers of the Santa Marta pediatric dispensary in Paul VI Audience Hall in the Vatican on December 14, 2013 27/40 December 2013 Pope Francis holds a scarf of Argentine football team San Lorenzo of which he is a fan, during his visit to the Sao Jeromino Emiliani church at the Varginha favela in Rio de Janeiro GETTY IMAGES 28/40 December 2013 Pope Francis wears his papal vestment during his inauguration mass at St Peter's square as Latin America's first pontiff GETTY IMAGES 29/40 December 2013 Pope Francis wears a Fisherman's Ring, made of gold-plated silver, symbolising the Holy Father's role as a 'fishers of men' GETTY IMAGES 30/40 January 2014 "The Times They Are A-Changing" indeed: Pope Francis waves on his Rolling Stone cover shoot 31/40 5 January 2014 A seagull flies past pope Francis as he arrives for the Angelus noon prayer he celebrates from the window of his studio overlooking St. Peter's Square at the Vatican on Sunday 5 January AP 32/40 6 January 2014 The lamb of God. The pope has a lamb put around his neck by a woman dressed as a character from the nativity scene at Church of St Alfonso Maria dei Liguori in the outskirts of Rome 33/40 13 January 2014 Pope Francis baptises one of 32 babies during a mass in the Sistine Chapel at the Vatican 34/40 14 January 2014 Pope Francis being presented with a Harley Davidson Dyna Super Glide motorcycle in Vatican 35/40 22 January 2014 Pope Francis greets the crowd as he arrives for his general audience at St Peter's square on January 22, 2014 at the Vatican AFP/Getty Images 36/40 January 2014 Pope Francis at the weekly papal audience in Rome, January 2014 Rex Features 37/40 February 2014 A close-up of Pope Francis' passport 38/40 19 February 2014 Facing some challenges. A gust of wind blows Pope Francis' mantle as he reads his speech during his weekly general audience in St. Peter's Square 39/40 26 February 2014 Pope Francis kissing a child dressed as Pope as he arrives in Saint Peter's Square to lead his Wednesday's General Audience, in Vatican City AP 40/40 5 March 2014 At work, in concentration. Pope Francis blesses the altar in the Santa Sabina church in Rome on March 5, 2014, as he celebrates the mass for Ash Wednesday, opening Lent

Such a small step is a far cry from the early heady days of ecumenism when it was widely assumed that unity was just a few years away.

Things had moved swiftly after the meeting by Archbishop Geoffrey Fisher and Pope John XXIII in 1960 – the first time an Archbishop of Canterbury had visited to the Vatican for 600 years. Pope John asked when the Anglicans would return to the Catholic fold. Archbishop Fisher replied: “It is not a question of returning, but going forward together.” His words became the model for a new relationship which was affirmed when John XXIII’s revolutionary Second Vatican Council (1962-65) recognised the validity of baptism by other Christian denominations.

In a gesture of massive significance, in 1966, Pope Paul VI gave an episcopal ring to Archbishop Michael Ramsey – which Archbishop Welby wore this week on his visit to Rome. A year later an Anglican–Roman Catholic International Commission (ARCIC) began unity talks. By clarifying old misunderstandings and embracing new scholarship it resolved many of the divisions which had bedevilled the two churches since the Reformation.

Much of ARCIC’s work is safely banked. When Rome’s top ecumenist, Cardinal Walter Kasper, called a meeting of Catholics, Anglicans, Lutherans, Methodists and Reformed churches in 2010 it found, one insider said, “not one single area of theology in which we do not have some measure of agreement”. This was not just a clever repackaging of old disputes. It is a real growth in understanding.

But until recently ARCIC had hit the buffers. When Rome took an extraordinary 10 years to respond to one key ARCIC agreement many Anglicans lost patience and went ahead with the ordination of women and more liberal attitudes to gays.

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In response the Vatican pulled the plug on the International Anglican-Roman Catholic Commission on Unity and Mission (IARCCUM). Pope Benedict XVI’s unilateral decision in 2009 to set up an Anglican Ordinariate to poach dissident Anglicans to Rome caused further resentment.

Yet things have clearly begun to change. Pope Francis and Archbishop Welby have similar visions. Both are no-nonsense characters with a “sleeves rolled up” approach to making change happen. Yet both see theological union as crucial. They have no patience with the “let’s agree to disagree on theology and just open a food bank together” approach.

In Rome Archbishop Welby – who despite his evangelical background, has a Benedictine spiritual director and has invited a French Catholic religious community, Chemin Neuf, to live in his home in Lambeth Palace – said that Anglicans and Catholics had to “get away from being quite comfortable with the fact we live separately”. Without theology, he said, the churches will become “just another NGO with a lot of old buildings”.

The renewed talk of unity is more than a pious aspiration. A third round of ARCIC talks has had meetings so far in Bose, Hong Kong, Rio and Durban. They have shifted the focus away from what divides the two churches to “receptive ecumenism” – what each side has to learn from the other.

At the heart of their discussions is how the two Communions go about making decisions. There are huge contrasts: Catholicism is heavily centralised whereas in Anglicanism authority is dispersed between many churches in many nations. Division is part of the Protestant DNA. And Anglicans are more divided among themselves now than ever before.

But Pope Francis clearly wants to change the governance of the Catholic Church so it is less like a mediaeval monarchy and more open to the wisdom and insights of all its members.

Given the practical difficulties posed by issues of gender and sexuality it is hard to see what unity between Catholics and Anglicans might look like – certainly not uniformity. But if the intellectual difficulties are greater now than 50 years ago, emotionally the two churches are closer than at any time since the reign of Henry VIII.

Archbishop Welby this week presented Pope Francis with a cutting from the giant fig tree planted in Lambeth Palace by the last Catholic Archbishop of Canterbury, Reginald Pole (1500-1558). What fruit it will bear, and when, is hard to predict. But hope is a theological virtue. For the past five decades the two churches have been moving on parallel lines. It feels as though, at last, those lines may be once more converging.

Paul Vallely is the author of ‘Pope Francis – Untying the Knots’