First a little history: The Roman Catholic Church and the Eastern Orthodox Church split apart in the "Great Schism" in 1054. This split was due to various doctrinal disagreements. The Church of England split from the Roman Catholic Church in 1534 because the pope would not annul King Henry VIII's marriage to Catherine of Aragon. There has been talk about reconciliation over the past several years with only limited progress.
Now Justin Welby, the Archbishop of Canterbury, is going to meet with Ecumenical Patriarch Bartholomew in Istanbul. The Patriarch is the so-called first among equals of the Orthodox patriarchs. He is the Archbishop of Constantinople and New Rome. He occupies the First Throne of the Orthodox Christian Church.
According to the attached article from "Ecumenical News", Welby is hoping to "contribute to the goal of Christian Unity. Pope Francis will be meeting with Patriarch Bartholomew in Jerusalem in May.