Medieval English composer John Cooke is one of the few composers in the Old Hall Manuscript about whom we know something. He is represented by nine pieces in that source as "Cooke"; an additional, incomplete manuscript of one of his two settings of the Credo gives his first initial as "J," leading to the generally accepted speculation that his first name was John. Although the name was common in medieval England, he is identifiable with a singer who arrived at Cambridge in 1402 or 1403. Cooke sang in the choir of the Chapel Royal, was elevated to the status of chaplain in 1413, and in 1415 he was part of the retinue that followed Henry V into the battle of Agincourt. In 1417, Cooke was named a canon of the church of Hastings, but by 1419 he was out of all of his posts; as an unknown hand unsuccessfully attempted to erase some of Cooke's compositions from the Old Hall, it is assumed that Cooke suffered some sort of fall from grace. Afterwards, there are several John Cookes on the rolls with whom he might be identified -- one candidate, a layman in the Chapel Royal who died in 1455, has been ruled out. However, the man who probably was John Cooke the composer turned up as a singer in St. Paul's Cathedral in 1426 and served there until his death in 1442, even briefly achieving the status of vice cardinal. Cooke is represented with more frequency in the Old Hall than any other composer apart from Leonel Power and Thomas Damett. Cooke's works are found both in the "old" and "new" layers of the Old Hall, and he may have been involved in compiling this source. Cooke's compositions strongly reflect the influence of Power, and his most famous work is the isorhythmic motet Alma proles regia/Christi mules/Ab inimicus nostris, which may have some internal historical relationship to the Agincourt campaign.