Task: Question Answering
Input (English): Passage: Bacon's output is characterised by sequences of images. He told Sylvester that his imagination was stimulated by sequences and that "images breed other images in me". His series were not always planned or painted in sequence; sometimes paintings are grouped for convenience but vary in execution and tone. The idea for the head series came after he returned penniless, late in 1948, from a stay in Tangier. In the previous three years he had been unable to find a voice; the last surviving canvas from this period is his Painting (1946). Although he continued to paint, he was a ruthless self-critic, given to slashing canvases with blades, and no works survive from between 1947 and the winter of 1948. Gallerist Erica Brausen offered Bacon the opportunity of a solo show for the opening of her new Hanover Gallery. He agreed, but had nothing in reserve to hang. In following years, Brausen became perhaps the most important of Bacon's early champions; she arranged this showing—his debut solo exhibition—publicised him widely and organised viewings for international buyers.Already 40 years old, Bacon viewed the exhibition as his last chance and applied himself to the task with determination. Because he had destroyed all his output of the last three years, he had little choice but to present new works. He did not have a grand plan when he agreed to the show, but eventually found themes that interested him in his Head I of the previous year, and executed five progressively stronger variants in the final weeks before the November exhibition, completing the series barely in time for the opening. 
Question: What is the name of the person who executed five progressively stronger variants in the final weeks before the November exhibition?
Output (English): Bacon.