Pope Benedict XVI’s shock resignation may be virtually unheard of in modern times but the system that will choose the Catholic Church’s new leader follows centuries of well-rehearsed and high secretive tradition. It is a process that has, by and large, enabled successors to be picked quickly and we could even see a new Pontiff enthroned before Easter Sunday.

The task falls to the College of Cardinals who convene in secret and are locked inside the Vatican until a new Pope is elected. Each member, who must be younger than 80 years old, is sworn to secrecy. Every day two ballots are taken in the morning and two in the afternoon. Once they are counted the ballots are burned. If one single candidate receives a two-thirds majority, a new Pope is elected and the smoke coming out of the chimney of the Sistine Chapel is changed from black to white.

Historically the papal conclave must meet no sooner than 15 days and no later than 28 days after a Pope’s death. But because Benedict has chosen to step down and has given the advance date of 28 February as his last day in office, there is no need for a traditional mourning period which should mean that the College of Cardinals will be meeting by the second week in March at the latest. But they may even decide to meet even sooner.

Speculation is now mounting over who could become his successor. Technically any baptised Roman Catholic male can be made the Bishop of Rome but the Pope has always been chosen from the ranks of Cardinals since 1378.

Given that the vast majority of the world’s one billion Catholics now live in the developing world, excitement is already mounting that the new Pope will be an African or Latin American Cardinal.

The difficulty with such predictions is that no-one other than the Cardinals themselves witness what happens inside the Sistine Chapel. After John Paul II’s death in 2005 many commentators were convinced that the new Pope would be African or Latin American. But the College of Cardinals has a distinct geographical bias, with half its voting members from Europe despite the fact that the continent only accounts for 25 percent of Catholics worldwide. When the time came to pick John Paul’s successor, they went for a fellow European and a man who had earned himself the nickname “God’s Rottweiler” because of his adherence to traditional orthodoxy.

The election of a non-white Pope would mark a radical break from 1,500 years of history (there have been three Pope who originated from Africa, the last of whom Pope Gelasius, died in 496AD).

The two African front runners, Cardinals Peter Turkson form Ghana and Nigeria’s Francis Arinze, have a long history of inter-faith dialogue with Muslims and could help build bridges following Pope Benedict’s lacklustre ecumenism. But their strictly orthodox views of homosexuality would cause friction with more liberal Catholics in the West.

Latin America’s long history of liberation theology means some of the most powerful cardinals from that continent could bridge the social divide between liberals and conservatives. The leading candidates there seem to be Odilo Scherer, archbishop of the huge diocese of Sao Paolo, or the Italian-Argentine Leonardo Sandri, now heading the Vatican department for Eastern Churches.

Two senior Catholic figures - archbishop Gerhard Mueller (who now holds the pope's old post as head of the Congregation for the Doctrine of the Faith) and Swiss Cardinal Kurt Koch (head of the Vatican department for Christian unity) have both given recent interviews saying the Catholic church would benefit from a Latin American Pope.

But there’s every chance the next leader could still be another European. The Italians are also known to be keen on seizing back the papacy with Milan’s Angelo Scola, the current head of the Pontiifical Council for Culture Gianfranco Ravasi and the Vatican’s top diplomat Tarcisio Bertone are possible front runners.

Elsewhere, Canadian Cardinal Marc Oullet – the current head of the Congregation of Bishops – and New York’s notoriously conservative cardinal Timothy Dolan are considered potential “new world” contenders.

Popes in waiting? The top candidates

Leonardo Sandri: A top contender to become Latin America’s first Pope, Argentinian Cardinal Sandri is currently the head of the Vatican’s Eastern Churches department.

Odilo Scherer: As Archbishop of Sao Paulo, Cardinal Scherer has the largest diocese in the largest Catholic country. He is conservative in his country but would rank as a moderate elsewhere which is why he might be attractive to all sides.

Peter Turkson: The top cleric in Ghana is probably the strongest candidate to become the first African Pope in 1,500 years. Currently head of the Vatican Justice and Peace Bureau he is very conservative on homosexuality.

Francis Arinze: Like Turkson, Cardinal Arinze is highly conservative on divisive issues such as homosexuality. But he has a good track record of dialogue with Muslims, something Benedict lacked.

Angelo Scola: The Italians are known to be keen on taking back the papacy and Milan’s Archbishop, Cardinal Scola, is considered their favourite candidate. He also has a good track record on Christian-Muslim relations.

Marc Ouellet: The best chance North America has of producing its first Pope, Cardinal Ouellet is one of the Vatican’s most senior officials as head of the Congregation of Bishops.