LONDON.- Unseen in half a century, Francis Bacon’s magnetic portrait of Lucian Freud just sold for £43.4 million / $52.8 million in Sotheby’s London saleroom - becoming the most valuable work of art sold at auction in London this season.

In its first market appearance, the painting became both the most valuable single panel and the most valuable painting by Bacon sold in London in GBP.

Painted in 1964, at the height of Bacon’s career, Study for Portrait of Lucian Freud illuminates the powerful dialogue of friendship and epochal rivalry which would engulf two titans of art history and spur them to create some of their greatest works. The pair had first met 20 years earlier and would go on to share an intense friendship for over 40 years until jealousy and petty rows would ultimately splinter relations forever in the mid-1980s.

Though their visual styles differed considerably, both artists were deeply committed to the human figure, painting each other on numerous occasions over the years. Indeed, for Bacon, Freud would become a recurrent - and one of the most significant - subjects of his work in the 1960s, a period of great artistic confidence during which he produced some of his finest portraits.

While Freud painted his subjects from life, it was black and white photographs, taken by their mutual friend John Deakin, which would become Bacon’s primary source material. In this case, Study for Portrait of Lucian Freud is based on a Deakin photograph taken earlier the same year, in 1964, showing Freud sitting on a bed, his arms outstretched, fists clenched, and white sleeves rolled up above the elbows. Of great personal significance, Bacon would keep these photographs with him for the rest of his life, and they were rediscovered torn, crumpled and splattered with paint in his studio following his death.

Study for Portrait of Lucian Freud was originally conceived as the central panel of a large-scale triptych, but separated by Bacon into three individual works shortly after it was created. All three panels hung together as part of a travelling exhibition to Hamburg and Stockholm, while the present painting was also shown in Dublin on its own. Today, the left-hand panel resides in a private collection, while the right-hand work belongs to the Israel Museum in Jerusalem.