Pope Francis delivers first Sunday prayers to crowd of 300,000 Pope Francis holds his first Angelus prayer from a window of the Apostolic palace (Photograph: Andrea Solero/EPA) More than 300,000 people have turned out to see Pope Francis deliver his first Sunday prayer from a window over St Peter's square, cheering and laughing as the new pontiff gave a simple message that contrasted in both style and content with his predecessor's weekly speeches. Four days after he was elected in a rapid conclave by cardinals of the Roman Catholic church, the 76-year-old again spoke off-the-cuff for his inaugural angelus, telling the crowds an anecdote about an old woman in Argentina who had so impressed him with her wisdom that he asked her: "Did you study at the [Pontifical] Gregorian [university]?" Francis spoke of what he said was God's never-ending capacity for mercy and urged people to be more forgiving of each other. "A little bit of mercy makes the world less cold and more just," he said. He praised a book written by German cardinal Walter Kasper - but then joked that he wasn't doing his PR for him. He brought the message to a halt with the words: "Have a good Sunday and a good lunch!" Pilgrims, many of them from Latin America, roared their approval. Many are hoping Francis will be able to make a break with the church's scandal-hit past, which has been dominated most significantly by clerical sex abuse but also by reports of a bitterly divided and unruly Roman curia. Earlier on Sunday, Francis startled passers-by in the Vatican as he emerged unannounced from a side-gate. He then led mass at the small church of St Anna in the Vatican, playing the role of simple parish priest as he pressed the flesh, kissed babies and embraced worshippers. The former cardinal Jorge Bergoglio told many of them: "Pray for me." The new pope - who will be officially installed at an inaugural mass on Tuesday in St Peter's square- has already showed his intention to break with the traditions sustained under Benedict XVI. His informal, straightforward style could not be more different from that of his predecessor, who was more likely to impress with his academic rigour than his sense of humour. But Francis, who is due to meet Benedict in Castel Gandolfo on Saturday, has shown his willingness to follow in the German's footsteps in at least one respect, sending out his first tweet from the @pontifex account that had lain dormant since its user's resignation on 28 February. "Dear friends," read the message posted on Sunday. I thank you from my heart and I ask you to continue to pray for me. Pope Francis. Though that message was in English, the native Spanish-speaker has so far kept to Italian in his official speeches and homilies, unlike Benedict, who used to flit between several languages in his Sunday prayers. Pope Francis is also able to speak English, French and German.