Nelson Mandela: London pays its respects outside South Africa House Mr Cameron finished by quoting Matthew 5:9: "Blessed are the peacemakers for they shall be called the children of God." Also visiting South Africa House was Boris Johnson, who told reporters that Mr Mandela should be revered as a secular saint. "If there was a secular system of canonisation in today's world," said the Mayor of London, "Nelson Mandela would be at the top of the list." In decades past, he conceded, some Conservatives had reviled Mr Mandela and described him as a terrorist. "That was clearly wrong," said Mr Johnson, "because what he was doing was opposing an absolutely vile system of government, and he did it by deploying the power of forgiveness." He himself, he added, had "never in my life deviated from the position of fervent admiration" for Mr Mandela; modern Conservatives, he said, felt the same respect. Visiting Britain in 1996 as President of South Africa, Mr Mandela addressed Parliament in Westminster Hall. On Monday MPs will pay tribute to him in the Commons during a specially organised debate. A service of thanksgiving for his life will be held at Westminster Abbey after the state funeral in South Africa on Sunday December 15. The Speaker of the Commons, John Bercow, placed a book of condolence in the Commons Library for MPs and members of parliamentary staff to sign. As a student in the 1980s, Mr Bercow joined the Federation of Conservative Students, among whose membership were many vocal critics of Mr Mandela. Yesterday, though, the Speaker described him as "an inspiration not only for his nation and for Africa, but for the world." In Parliament Square, the statue of the late statesman - unveiled in 2007 - stood almost engulfed in flowers. Around its feet lay flags, Springboks scarves, commemorative editions of the morning's newspapers. Scores of people gathered to take pictures. One young woman even clambered on to the plinth and, eyes tightly closed, gave the statue a hug. It was an image that somehow summed up the mourners" mood: grief overcome by love.