So just who did hang the unflattering paintings of a naked Brian Cowen, the Irish Prime Minister, in the country’s most prestigious art galleries?

Two unorthodox portraits — one in the National Gallery showing the Taoiseach on the toilet, and another in the Royal Hibernian Gallery showing him holding his Y-fronts — appeared mysteriously in Dublin among paintings of the country’s other famous citizens in more decorous poses.

The Irish media speculated that the prankster had created the artworks in an attempt to lift the nation’s spirits at a time of deep economic gloom. Judging by the chuckles of visitors and comments inundating the blogosphere, the stunt worked.

“Biffo on the bog”, was one gleeful response, referring to the Taoiseach by his nickname, which stands for “Big Ignorant F***er from Offaly”.

The artist reportedly walked calmly into the National Gallery carrying a shoulder bag. He then affixed a prepared caption for the picture to a free space among portraits of Michael Collins, William Butler Yeats and Bono, before hanging his canvas, undisturbed by security.

The caption read: “Brian Cowen, Politician 1960-2008. This portrait, acquired uncommissioned by the National Gallery, celebrates one of the finest politicians produced by Ireland since the foundation of the state.

“Following a spell at the helm of the Department of Finance during a period of unprecedented prosperity, Brian Cowen inherited the office of Taoiseach in 2008. Balancing a public image that ranges from fantastically intelligent analytical thinker to Big Ignorant F***er from Offaly, the Taoiseach proves to be a challenging subject to represent.”

One woman who saw the National Gallery portrait of the Taoiseach, pictured gripping a toilet roll in one hand, commented: “Well at least that is one mess he has been able to clear up.”

The Sunday Tribune reported that the portrait of Mr Cowen wearing nothing but his glasses hung for more than an hour, with hundreds of patrons believing it to be a genuine part of the collection. After security guards removed it, police were called to examine the portrait and CCTV evidence.

The guerrilla artist, emboldened by his success, went on to hang a second portrait of the Taoiseach in the Royal Hibernian Gallery. The second naked portrait depicted a portly Mr Cowen, still in his glasses, holding a pair of blue and white pants in his left hand.

One woman who saw the work was impressed enough to make an offer.

Dublin is rife with rumour about the identity of the artist. Ian Whyte, of Whyte’s Gallery, said: “It was certainly a professional job; the two paintings were both very well executed. They are actually better than the work of a few artists I thought it might be. Everyone will be talking about it until the identity is revealed.

“No crime was committed, whoever it was didn’t take anything. In fact, he donated something.”

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