English composer. He enjoyed the favor of King Edward III, who sent him to collect money from the Kentish monasteries and rewarded him with a canonry at Windsor (1362 -1373) and also with other ecclesiastical posts including posts at Exeter and Wells cathedrals. In 1384 St George's, Windsor, possessed a roll of MS music bequeathed to it under Aleyn's will. His complex isorhythmic motet Sub Arturo plebs in the Chantilly MS may have been written for the celebrations on April 23, 1358 of the victory at Poitiers; its texts contain a list of English musicians and a list of famous theorists including Pythagoras, St Gregory, Boethius and, at the end, Aleyn himself. He is represnted in the Old Hall manuscript.
Distinguished from John Aleyn, (139(6)- ?), a musician in service to John of Gaunt and John Aleyn, (d. 1437?), minor canon of St. Paul's Cathedral.