The Pope has warned against the culture of celebrity in a speech to thousands of young people in London during his Papal tour of the UK. In a veiled attack on the world of entertainment, Pope Benedict XVI told the youngsters that having fame and money is not enough to be happy. The Pontiff made the remarks to around 4,000 school pupils and young children at a "big assembly" gathering at a Catholic college in Twickenham. But the second day of his UK tour has been marred by the arrest of five men by police investigating a suspected plot to harm the Pope, according to Sky News' sources. Scotland Yard officers swooped after information emerged that he could be in danger. Speaking at St Mary's University College earlier, his Holiness said: "We live in a celebrity culture and young people are often encouraged to model themselves on figures from the world of sport or entertainment. "My question for you is this: What are the qualities you see in others that you would most like to have yourselves? What person would you most like to be?" He invited the children to "become Saints" and not to be content with second best. The Pope added: "Having money makes it possible to be generous and to do good in the world but on its own it is not enough to make us happy. "Being highly skilled in some activity or profession is good but it will not satisfy us unless we aim for something greater still. It might make us famous but it will not make us happy." He told them: "The key to it is very simple - true happiness is to be found in God." He also said schools must "provide a safe environment" for children and, in an apparent reference to the abuse scandal, the Pope said teaching should be carried out in an atmosphere of "respectful and affectionate trust". The west London suburb of Strawberry Hill near Twickenham was turned into a riot of colour as schoolchildren and members of the clergy descended on the area. But the huge security operation surrounding the visit led to unusual scenes outside St Mary's University College. Streams of bemused nuns waited in long queues to go through security scanners at the Catholic college. Their veils were inspected and rosary beads removed from handbags as they negotiated security. One monk looked on incredulously as his crucifix was inspected and his habit frisked by police. The Pope began the second day of his official Papal Visit with a private mass in Wimbledon after flying into London last night. He then travelled to St Mary's University College, where he performed a special service for young people in an event to celebrate Catholic education. Protesters had also gathered outside the college, with some holding banners reading "Holy Joe Ratzinger" and "From Hitler Youth to Papacy", but they numbered dozens rather than hundreds. But the Pope was greeted by raucous cheers as he took to the stage for the event and the crowd of schoolchildren waved flags and sang as he arrived at the sports field in the Popemobile. The Pontiff will head next to central London, where he will address the Houses of Parliament and meet the Archbishop of Canterbury, Dr Rowan Williams. In the evening Pope Benedict will attend Evensong at Westminster Abbey. Source: Sky News