English composer. He was associated during the first part of his career, from about 1413 until 1421, with the Household Chapel of Thomas, Duke of Clarence (brother to Henry V and thus heir presumptive to the throne). Later, from 1438 through 1445, he served as the first Master of the Lady Chapel Choir at Canterbury, although his association with Canterbury began as early as 1423. The middle period of his life, between 1421 and 1438, is obscure, though some connection with the Chapel Royal seems likely, probably involving time spent abroad among the English possessions in northern France. Whilst the bulk of his extant works is found in the Old Hall MS, other sources provide us with an important Mass (based on Alma redemptoris mater as cantus firmus) and several late motets in a new, more lyrical style. The style of his later works shows Power clearly moving towards the consonant, less rhythmically complex sound of the 'contenance angloise' ('English countenance'), typified by the music of John Dunstable and composers such as Bedyngham, Plummer and Frye. This music, for which English musicians became famous, is characterised by a fullness of sound, sweetened by the almost constant presence of thirds and sixths, and rendered graceful by the suavity of the interlacing melodic contours.
With Dunstable, he was one of the most influential English composers on the Continent. He also wrote a treatise on Descant.