Right - with St. Margaret in Westminster (not Herts.) FindMyPast reveals the following all baptised at St. Margaret, Westminster:
James b.14/5/1781, bp.11/6/1781, son of James Meredith Parratt and Sophia Maria
Thomas b.1/5/1782, bp.11/7/1782 ditto
William b.4/4/1783, bp.2/5/1783 ditto
Sophia Elizabeth b.19/10/1785, bp.15/11/1785 ditto
Sarah Charlotta b.2/10/1786, bp.31/10/1786 ditto
Edward b.28/10/1787, bp.28/11/1787 ditto
Maria Sophia b.11/12/1788, bp.20/1/1789 ditto
Hillebrant Meredith b.12/2/1791, bp.7/4/1791 son of James Meredith Parrott (wife's name missing from original entry)
plus with surname transcribed as Perrott:
Elizabeth Caroline b.10/9/1795, bp.26/10/1795 dau. of James Meredith Perrott and Sophia Maria
James Meredith Parratt, widower, married Sophia Maria Cooper, of St. Gregory, London - by licence - on 17/8/1780 St. Margaret, Westminster
James Meredith Parratt's will - probate 2/4/1798 - copy of will is on Ancestry.
James Meredith Parratt b.20/9/1739, bp.7/10/1739 St. Margaret, Westminster to Thomas and Elizabeth.
Annette