A stole is a large piece of cloth worn around a clerics neck. It is a symbol of his ministry and spiritual authority. It is modeled after the Jewish prayer cloth called a tallit. The tradition obviously comes down to us from the apostolic age, as Jewish apostles wore tallitot (plural for tallit) while preaching the gospel to Gentiles. This is why the stole is seen as a symbol of authority to Christians.
Anyway, this particular photograph is very interesting because you see the pope was sitting in Westminster Abbey, when it was taken, where he was to address the spiritual leaders of the Church of England. Westminster Abbey is the primary place of worship for Anglicans. It's sort of like the Anglican answer to St. Peter's Basilica in Rome. The stole he wore around his neck was not his normal stole. It was the one worn by Pope Leo XIII (1878-1903 AD). Pope Leo XIII was the pope who elevated John Henry Newman to the office of cardinal-deacon, so since the pope would beatify Cardinal John Henry Newman two days later, it somewhat explains his use of Pope Leo's stole. However, there is a deeper symbolism here, and this pope is well known for teaching through symbols. Pope Leo XIII was also known as the pope who officially declared Anglican religious orders invalid...
Wherefore, strictly adhering, in this matter, to the decrees of the pontiffs, our predecessors, and confirming them most fully, and, as it were, renewing them by our authority, of our own initiative and certain knowledge, we pronounce and declare that ordinations carried out according to the Anglican rite have been, and are, absolutely null and utterly void.Anglicans are fully aware of this, and the Catholic Church has never once altered of revoked this decree. To this day, Anglican priests who reconcile with Rome are re-ordained properly according to authentic apostolic orders. In declaring Anglican orders invalid, Pope Leo XIII leveled his charge against the British queen, the Protestant British government, and the entire British Empire as well as the whole Anglican Communion. The schismatic actions of King Henry VIII in 1534, and his daughter Elizabeth I in 1559, not only broke the Church of England away from Rome, but they effectively established a whole new religion, wherein the British monarch (king or queen) acted as "pope" with the Archbishop of Canterbury acting as his/her spiritual mouthpiece. The Church of England (Anglicanism) was born, and it was the monarch's church, an extension of the monarch's political and "spiritual" power. What followed was the rise of the British Empire, and it was indeed British schism with Rome that spawned the birth of imperial rule. The monarch armed with the royal military in one hand, and his/her own royal religion in the other, could exercise full physical and spiritual supremacy over his/her subjects wherever the British flag was planted.-- Apostolicae Curae, 36
Not long after Leo XIII's encyclical declaring the nullity of Anglican orders, the power of the British Empire began to wane. By World War I (1914-1918 AD) the empire was crippled. By World War II (1939-1945 AD) it was finished. Today there is nothing left, save an exoskeleton called the "Commonwealth of Nations" which has not amounted to much, and it is universally agreed by everyone that the British Empire is defunct. The monarchy itself faces irrelevancy while the Anglican Communion has become a disheveled group of member-churches united in little more than name. The Anglican religion and the British empire were one in the same. They were extensions of the Protestant monarch's power. Both are now relics of history. This was the cost of England's schism with Rome. In the short run it brought England wealth and power beyond imagination. In the long run it brought political, social and spiritual bankruptcy. Today, Islam threatens to take over England as it's number one practiced religion.
So on September 17, 2010 Pope Benedict XVI sat in the highest chapel of the Church of England, before the highest prelates of the Church of England, wearing the stole of the man who declared all of their clerical orders totally and completely invalid. What was their response to this symbolic act? They applauded him!
Two days later, September 19, 2010 he beatified John Henry Newman, the high profile Oxford reformer of Anglicanism who reconciled with Rome and became a Catholic cardinal. Obviously, the pope's message to Anglicans here was to follow John Henry Newman's example. Then he instructed the Catholic bishops of England to make wide and generous provision for the Anglican converts that will soon enter the Catholic Church through the upcoming ordinariates.