The theme is taken from the opening bars of Couperin's famous keyboard Passacaille in B minor. An earlier composition for wind ensemble (1959) was also the result of a long standing affection that Horovitz has for the potent musical idea. The Fantasia is scored for eleven solo string parts, with optional tutti addition. Couperin's four-bar phrase (with its original harmonisation) is quoted in the middle section of the work. The opening theme by Joseph Horovitz undergoes a gradual metamorphosis towards this central point; Couperin's theme is then developed and eventually guided back towards a short recapitulation of the opening. The work was completed in April 1962, and premièred by Philomusica of London under Sir Adrian Boult at the Victoria and Albert Museum in July in 1962.