His tenure of the earldom was marked by an internal family fight over possession of the marcher lordship of Gower, which was claimed by his uncle Henry supported by his grandmother Margaret, whose dower it was.

[1] Earl William may have hoped his great marriage to the wealthy Yorkshire heiress Matilda de Percy would help redeem his fortunes.

She survived her husband by two decades, and the large dowry she enjoyed from the earldom crippled it financially for two generations.

[2] William is said to have founded the hospital of St John of Warwick and was a patron of several religious houses.

He did however have a bad relationship with the family foundation of the priory of the Holy Sepulchre in Warwick, which earned him a letter of rebuke from the patriarch of Jerusalem.