when did he become the prime minister?
In 2010
David Cameron
On 11 May 2010, following the resignation of Gordon Brown as Prime Minister and on his recommendation, Queen Elizabeth II invited Cameron to form a government. At age 43, Cameron became the youngest Prime Minister since Lord Liverpool in 1812, beating the record previously set by Tony Blair in May 1997. 
is university of oxford the same as oxford university UNANSWERABLE where is this university located? Oxford, Oxfordshire, England are there any clubs in this institute? Yes, Bullingdon Club what is this club about? It is a private all-male dining club for Oxford University students is there a particular dressing style that one has to follow here? Yes, bespoke tailored tailcoats in dark navy blue, with a matching velvet collar, offset with ivory silk lapel revers, brass monogrammed buttons, a mustard waistcoat, and a sky blue bow tie has it been referred to in any media? Yes, in the UK Channel 4 docu-drama "When Boris Met Dave" what is this show about? Investigates the shared past of David Cameron and Boris Johnson who is the former ? A British Conservative Party politician who served as Prime Minister of the United Kingdom
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David Cameron [SEP] Prime Minister (2010–2016)
On 11 May 2010, following the resignation of Gordon Brown as Prime Minister and on his recommendation, Queen Elizabeth II invited Cameron to form a government. At age 43, Cameron became the youngest Prime Minister since Lord Liverpool in 1812, beating the record previously set by Tony Blair in May 1997. In his first address outside 10 Downing Street, he announced his intention to form a coalition government, the first since the Second World War, with the Liberal Democrats. Cameron outlined how he intended to "put aside party differences and work hard for the common good and for the national interest." As one of his first moves Cameron appointed Nick Clegg, the leader of the Liberal Democrats, as Deputy Prime Minister on 11 May 2010.