Can only find the three Holyland sisters, baptised to Fulcher and Barbara Holyland. Would be nice if they had a brother William, who married Sophia something, but not finding anything that matches that. Could Henry be Sophia's illeg son and father William was invented?. Henry wasn't baptised until he was almost 3 which seems a bit unusual.
Someone correct me if I'm wrong but they did appear to have a son named William.
Baptisms - St Michael & All Angels, Kingsnorth, Kent
26 Apr 1774 - Mary Holyland; Fulcheer & Barbara
23 Jul 1775 - Catherine Holyland; Fulcher & Barbara
14 Nov 1776 - William Holyland; Fulcher & Barbara
19 Oct 1777 - Jane Holyland; Fulcher & Barbara
Baptisms - Finsbury, London
15 Dec 1779 - Sophia Holyland; Fulshar & Barbara; salesman; born 25 Nov
24 Mar 1782 - Barbara Eleanor Holyland; Fulshar & Barbara; salesman; born 19 Feb
This looks like it may be daughter Jane although I can't find the actual marriage record:
Oxford Journal
19 Apr 1806
Married
At Christ Church, Mr Beel, of Commushall Row, to Miss Holyland, of Newgate Street.
Pallot's Marriage Index:
Jas. Hickson Beal
Jane Holyland
1806
Christchurch Newgate, London
The Holyland family do seem to have a connection to Newgate Street:
London City Directories [?] - 1802:
Holyland Fulcher, carman, 8, Newgate-st and Holborn Bridge
Holden's Triennial Directory - 1805-1807:
Holyland Fulcher, carman, 8, Newgate st