Laurence was born in 1608.
He married Catherine Murray c.1654 at which time he was Parson of Fossoway.
He died in 1658 leaving two sons
- James Mercer (d.s.p.)
- Laurence Mercer (1657-1720)
Catherine was the daughter of John Murray, Minister of Kinkell, brother of the Laird.
She died in 1699.