[2] His grandfather, Peter de la Metgée (1665-1735), was a French Huguenot who fled to Ireland to avoid religious persecution after the revocation of the Edict of Nantes in 1685.
He sat in the Irish House of Commons as member for Ardee in 1776 and subsequently for Ratoath in 1783 (where he was succeeded as MP by his brother John; it was effectively in the gift of Peter's father-in-law's family, the Lowthers).
He left his estate to his children by Eleanor Archdeacon, who was by then deceased, and whom he apparently regarded as his second wife, although there is no conclusive evidence that they were legally married.
Peter's mother Anne, who died in 1792, had left him nothing in her will: according to family tradition, this was because she knew about and deeply disapproved of his relationship with Eleanor.
The number of duels he fought was not in itself remarkable by the standards of the time, but he was considered eccentric for fighting his own brother-in-law, Sir Edward Crofton, 2nd Baronet.