The leader of the Catholic Church in England and Wales has said the new Pope may temper some of his views in public.
A nun prays at Westminster Cathedral on Tuesday
The Archbishop of Westminster, Cardinal Cormac Murphy-O'Connor, said: "The Pope now has a platform and a place he didn't have before.
"Now he has much wider responsibilities and I think he's aware of that."
Pope Benedict XVI opposes birth control and the ordination of women, supports the celibacy of the priesthood, and has spoken out against homosexuality.
Formerly Cardinal Joseph Ratzinger, he has also said people who support the "grave sins" of abortion and euthanasia should be denied Communion.
Cardinal Murphy-O'Connor said it had been a "special" moment when the Catholic Church's cardinals elected their new leader.
"When the majority was reached... there was sort of a gasp all round, and everybody clapped," he said.
"He [Cardinal Ratzinger] had his head down - I think he must have said a prayer.
"He couldn't have been unaware that this was quite likely to happen, but that moment when it actually does is a very special one."
The Queen has led British leaders in congratulating the newly elected Pope.
Prime Minister Tony Blair has sent his best wishes to the Vatican, saying he looked forward to continuing co-operation with the Holy See on issues including Africa and development.
Charles Kennedy, Liberal Democrat leader, offered his "profound good wishes", while senior Tory Michael Ancram wished him "strength and courage".
BBC correspondent Peter Gould said that some Catholics "who want to reform the Church may be less happy" at the appointment.
Father Ray Lyons, of the Portsmouth Diocese, said he was "shocked" at the decision, saying the new Pope lacked a "reform agenda".
"He is a great thinker who will probably go along the same lines as his predecessor, but he is not what I felt was needed," Father Lyons said.
The Anglican Bishop of Oxford told BBC News he was "disappointed", pointing out "the vast majority of Catholics around the world are young, are poor and are women".
"One can quite properly ask whether a 78-year-old West European male is the best person to articulate the very pressing concerns of these literally millions of people," the Right Reverend Richard Harries said.
Several Britons who were in St Peter's Square have told of the "electric" scenes in the Vatican on Tuesday night.
Software director John Farmer, 36, from Edinburgh, saw the white smoke appearing from the chimney of the Sistine Chapel - the signal that the cardinals had decided on a new Pope.
He said: "When that moment finally came, it was an unbelievable sense of joy."
Kim Campbell, 16, from Dublin, said: "It was so exciting to see the new Pope come out. Everyone applauded and cheered."