Lady Howth, Joan Beaufort St Lawrence was born circa 1434 in Somerset, Somerset, England to Edmund Beaufort, 2nd Duke of Somerset (1406-1455) and Eleanor Beauchamp (1408-1467) . She married Robert St Lawrence (1440-1485) 1478 JL in County Dublin, Ireland.
Robert St Lawrence (1440-1485), 3rd Baron Howth, married firstly Alice White, daughter of Nicholas White of Killester, and by marriage acquired the manor of Killester. I believe she died prior to 1478 when Robert remarried to Joan Beaufort.
In 1478 he made a second and politically significant marriage to Joan Beaufort, daughter of Edmund Beaufort, 2nd Duke of Somerset. Somerset's seemingly remote claim to the English Crown as the legal heir of John of Gaunt was vindicated by his cousin Margaret Beaufort"s son Henry VII. The St. Lawrence family, unlike most of the Anglo-Irish nobility, were reliable supporters of the Tudor dynasty.
Some sources state that his second marriage was childless, but his eldest son Nicholas, who was born about 1460, must have been about twenty years older than his second son Thomas, who was at law school in 1503 and survived until 1553, so it is likely that Thomas and his younger brothers were children of their father's second marriage. Joan remarried Sir Richard Fry and died in 1518.
Children
| Name | Birth | Death | Joined with |
| Thomas St Lawrence (c1480-) | |||
| Walter St Lawrence (c1482-) | |||
| Christopher St Lawrence (c1483-) | |||
| Genet St Lawrence (c1484-) | |||
| Anne St Lawwrence (c1485-) | |||
Siblings