| Father | William de Montague 1st Earl of Salisbury, 3rd Baron Montagu and King of Mann (1301 - ) |
| Mother | Katherine de Grandison Countess of Salisbury ( - ) |
| Sibling | Sybyl de Montagu (1330 - ) |
| Sibling | Sir Knight John de Montagu 1st Baron Montagu & 2nd Earl of Salisbury (1328 - ) |
| Sibling | Margaret de Montagu (1354 - 1388) |
| Sibling | Robert Montagu ( - ) |
| Sibling | Philippa de Montagu (1332 - 1381) |
| Sibling | Alice de Montagu (1325 - 1360) |
| Sibling | Agnes Montagu (1331 - ) |
| Sibling | Elizabeth Montagu (1325 - 1359) |
| Sibling | William de Montagu 2nd Earl of Salisbury (1328 - 1397) |