Guillaume was the son of unknown parents. The date and place of his birth have not been found.
His wife was Gundred de Varennes. They were married, but the date and place have not been found. They had no known children.
| Attribute | Date | Description | Details | Source | Multimedia | Notes |
|---|---|---|---|---|---|---|
| Nobility Title | seigneur de Kendal et Lonsdale dans le Westmoreland |