(also spelled William de Longchamp or William de Longchamps) He was born in Normandy. After service with Geoffrey, duke of Brittany, he joined Richard (later Richard I) and John in their uprising (1189) against their father, Henry II, and was made chancellor of Aquitaine. Upon Richard's accession (1189) to the throne, William was made chancellor of England and bishop of Ely.
When the king went on crusade in 1190, William was appointed joint justiciar, and within the same year he had ousted the other justiciar and been appointed papal legate, thus becoming the acting head in England of both state and church.
His strong administration was very unpopular, and in 1191 a series of disputes led to a rebellion by the king's brother John and the barons. A settlement was reached, but shortly thereafter the justiciar's high-handed arrest of Geoffrey, archbishop of York, provoked another uprising, and William was deposed from office.
In 1193 he joined the captive Richard in Germany and was active in the negotiations to secure his release. He remained chancellor to the king and visited England with him in 1194.
Of Longchamp's homosexuality, Giraldus Cambrensis claims that “the more outrageous the sexual act, the more he liked it; that he made homosexuality so common that heterosexuals were ridiculed at court - “If you don't do what courtiers do, what are you doing in court?”; that a woman brought her daughter to him dressed as and trained to imitate a young man, but when the bishop undressed her and found she was a girl he would not touch her (“although she was very beautiful and ripe for the pleasures of the marriage bed,”); and that his homosexuality was so great that even descendants of his family were suspected of homosexuality".
Boswell warns that Giraldus' claims are so exaggerated, they may be based on little more than the standard English animus against the French overlords - but also notes that unlike other English diatribes against the invaders, his complaints against Longchamps are not about general sexual depravity, but concerned only with homosexuality. It is also important to note that male sexual relationships appear to have been commonplace at the court of the bisexual King Richard I.
There was a well-known line about Longchamps that the barons would trust their daughters with him, but not their sons.