Question: Which British Prime Minster belonged to a men-only dining club at the University of Oxford and was implicated in "Piggage"?

Context articles: Piers Gaveston Society
Chatham Dining Club
Piggate
Pythic Club
The Cannibal Club
Black Widowers
Posh (play)
The Literary Society
Myrmidon Club
The Riot Club

The Piers Gaveston Society is a men-only dining club founded in 1977 at the University of Oxford.
 It is named in honour of Piers Gaveston, favourite and supposed lover of King Edward II of England.
The Chatham Dining Club is a general interest Dining club based in London, United Kingdom.
 The Club was founded in 1910 by Captain Rupert Ommanney and Captain Guy Dawnay whilst they were students at the British Army Staff College in Camberley.
"Piggate" refers to an uncorroborated anecdote that during his university years former British Prime Minister David Cameron put a "private part of his anatomy" into a dead pig's mouth as part of an initiation ceremony for the Piers Gaveston Society.
 The anecdote was reported by Michael Ashcroft and Isabel Oakeshott in their unauthorised biography of Cameron, "Call Me Dave", attributing the story to an anonymous Member of Parliament who was a "distinguished Oxford contemporary" of Cameron's.
 Extracts from the book were published in the "Daily Mail" on 21 September 2015, prior to its publication.
The Pythic (or "P") Club is a secretive students' dining club at Oxford University, based in Christ Church.
The Cannibal Club was a Victorian dining club associated with The Anthropological Society, likely founded at the same time in 1863 by Sir Richard Francis Burton and Dr James Hunt.
 The club met in Bartolini's dining rooms near Fleet Street.
 Its official symbol was a mace carved to look like an African head gnawing on a human thighbone.
 The club's name is thought to derive from Burton's interested in cannibalism which he regretted that he never witnessed on his travels.
 Club members included: Richard Monkton Milnes, Charles Bradlaugh, Thomas Bendyshe, Algernon Swinburne, Sir James Plaisted Wilde, General Studholme John Hodgson and Charles Duncan Cameron.
The Black Widowers is a fictional men-only dining club created by Isaac Asimov for a series of sixty-six mystery stories that he started writing in 1971.
 Most of the stories were first published in "Ellery Queen's Mystery Magazine", though a few first appeared in "Fantasy & Science Fiction", "Isaac Asimov's Science Fiction Magazine", and the various book collections into which the stories were eventually gathered.
Posh is a play by the British playwright Laura Wade.
 It was first staged at the Royal Court Theatre downstairs in 2010.
 The play concerns an Oxford student dining club called "The Riot Club", a fictionalised version of the Bullingdon Club.
 The first production, produced during the British General Election, received favourable reviews.
The Literary Society is a London dining club, founded by William Wordsworth and others in 1807.
 Its members are generally either prominent figures in English literature or eminent people in other fields with a strong interest in literature.
 No papers are delivered at its meetings.
 It meets monthly at the Garrick Club. "
The Daily Telegraph's " online site called the club "Britain's most distinguished and discreet literary dining club".
The Myrmidon Club is a dining club elected from the male undergraduate members of Merton College, Oxford.
 Founded in 1865, it is one of the handful of such clubs with an almost continuous existence from the second half of the 19th century.
 It is thought to be the model for the Junta, the fictional club in Max Beerbohm's "Zuleika Dobson", of which the Duke of Dorset was for some time the sole member.
The Riot Club is a 2014 British drama film directed by Lone Scherfig and written by Laura Wade, based on Wade's 2010 play "Posh".
 The film stars Max Irons, Sam Claflin and Douglas Booth.
 It is set among the Riot Club, a fictional all-male, exclusive dining club at Oxford University.
 When the play "Posh" premiered, the Riot Club was often described as a thinly veiled version of the real-life Bullingdon Club, or High Trees Society, although according to Wade it is entirely fictitious.