In the United Kingdom, Christmas number ones are singles that top the UK Singles Chart in the week in which Christmas Day falls. The singles have often been novelty songs, charity songs or songs with a Christmas theme. Historically, the volume of record sales in the UK has peaked at Christmas. The Christmas number one is considered especially prestigious, more so than any other time of year. Christmas number-one singles have often also been the best-selling song of the year, though in recent years they have been released by reality television contestants and charity efforts. Due to the common practice of dating a chart by the date on which it is announced (the end of the sales week), the Christmas chart is dated before Christmas Day in the chart week (so the new sales week not still ended) containing 25 December. The most recent Christmas number one single is "Food Aid" by LadBaby. History The UK Singles Chart began in 1952 – appearing in the New Musical Express. The positions of all songs are based on weekly sales (from Sunday to Saturday until 2015, then from Friday to Thursday). Before 1987, they were released on a Tuesday due to the need for manual calculation. The emergence of a serious contest for the Christmas number-one spot began in 1973, when the glam rock bands Slade and Wizzard deliberately released festive songs in an effort to reach the top of the charts at Christmas, with Slade's "Merry Xmas Everybody" beating Wizzard's "I Wish It Could Be Christmas Everyday". The Christmas number-one single was not revealed on Christmas Day itself until 1994. From 2002 until 2014, the competition for the Christmas number one was dominated by reality television contests, with the winners often heading straight to number one in the week before Christmas. This trend began when Popstars: The Rivals contestants released the top three singles on the Christmas chart. Between 2005 and 2014, the winners of The X Factor took the number-one spot on seven occasions. In 2007, the X Factor single was such a strong favourite for number one that bookmakers began taking bets on which song would be the "Christmas Number Two" instead. Rage Against the Machine's 1992 single "Killing in the Name" outsold Joe McElderry in 2009 following a successful Facebook campaign against this trend. This made them the first group to get a Christmas number one with a