work on the Cenotaph. Contractors cleaned the stonework using steam and a poultice to remove dirt and algae and counter the effects of weathering and pollution. Somewhat controversially, the German president, Frank-Walter Steinmeier, was invited to lay a wreath at the Cenotaph on Remembrance Sunday 2018 to mark the centenary of the armistice, the first time a German representative had been present at the commemorations. Remembrance services The Cenotaph is the focal point for the National Service of Remembrance held annually on Remembrance Sunday, the closest Sunday to 11 November. In the Cenotaph's early years, the service was informal and crowds gathered round the memorial to pay their respects and lay tributes, but the ceremony gradually became more formal, and has changed little since the 1930s. Whitehall is closed to vehicle traffic and a two-minute silence is observed at 11:00am. After the silence, the crowd sings traditional hymns, accompanied by military musicians. The monarch and the prime minister (or their representatives) then lay wreaths at the Cenotaph, followed by other members of the royal family, politicians, and Commonwealth high commissioners. Afterwards, serving military personnel, veterans' associations, and other organisations march past and lay their own wreaths. Until the Second World War, the service was held on 11 November. It was moved to a Sunday to avoid interrupting wartime production, and has been held on a Sunday ever since. According to Paul Fussell, an American literary historian specialising in the cultural effects of the world wars, "to sense the British obsession with the Great War, all that is necessary is to stand at the Cenotaph [...] on any Remembrance Sunday and listen to the two minutes of silence," which he describes as "appropriately shocking in the context of the customary hum of traffic." Other annual ceremonies are also held at the Cenotaph, such as commemorations by individual regiments or veterans' associations, or on anniversaries such as Anzac Day (25 April). In 2000, relatives of soldiers executed for desertion or cowardice during the First World War joined the Remembrance Sunday parade for the first time, and in 2014 a representative of the Irish government laid a wreath on Remembrance Sunday for the first time, in memory of Irishmen who fought in the British armed forces in the First World War. The BBC began broadcasting special radio programming for Armistice Day in 1923, and began broadcasting the events at the Cenotaph live from