1. 19th Century and before

There are a number of relevant Harris family blogs and pages that can be referred to:

• Ancestry.com has a page relating to Tabitha Essen and James Harris (Marriage Entry of James Harris and Tabitha Essen Harrow St Mary Middlesex. 10 Oct 1809)
• http://mepnab.netau.net/h/harris.html
• http://familytreemaker.genealogy.com/users/g/o/l/Graeme-Bruce-Goller/WEBSITE-0001/UHP-0140.html

haze1773 has the following information
Richard Harris m Sarah
child James Harris b1760 (Harrow on the Hill) d 1797

John Nicholas b1678 m Mary James (b1678)
Children of John and Mary
Daniel b1701 (Harrow), Samual b1705 (Harrow) James Nicholas b 1709 (St Mary
Harrow) m Mary Roading b1710

Children of James Nichols and Mary Roading
Henry Nicholas b1732 d 1732, Anne Nicholas b 1736, Mary Nicholas b 1733 d
1768 m Richard Steptoe b1732 d 1801 (all the Nicholas' are born Harrow)

Children of Mary and Richard Steptoe
Mary b1757 (Harrow on the Hill) d 1827 m James Harris, William b1758 d
1759, Elizabeth b 1760, d 1760, Catherine b 1761

Steve Clarke has extensive research that includes the family of Mary Steptoe.
http://www.steve-clarke.com/main/familychart.php?personID=I13825&tree=main

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A couple of pages from the Parish Baptism Register - St Mary the Virgin Northolt 1701-1812 (split over three images).  Of interest are:
1757 March 28 Mary daughter of Richard and Mary Steptoe
1758 October 8 Daniel son of Richard and Mary Steptoe
1759 January 22 Elizabeth daughter of Richard and Mary Steptoe
1761 April 12 Catherine daughter of Richard and Mary Steptoe

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haze1773 has the following information cont/
Children of Mary Steptoe and James Harris
James b1783 d 1853 m Tabitha Essen b1792, Sarah b 1785, William b1785 d
1786, John b 1789, Mary b1791, d 1807, Thomas b1795

Children of James and Tabitha
Mary b1810, James b1812, d 1862, John b1814, 1873, Thomas b1816, William
b1818, George b1820, Matilda b1822, Pamela b1824, Alfred b 1827, Cornala
b1827, Tabitha b1829 d1901, Emma b1831, d1832 (all Harrow on the Hill)

The following information is based on research supplied by Lena Allen.

James Harris married Mary ?

Child of James Harris and Mary

James Harris b1783 Harrow on the Hill, d 6 Jul 1853

John Essen married Sarah

Child of John Essen and Sarah

Tabitha Essen b13 Jun 1791, Sherbourne Dorset, d?

James Harris married Tabitha Essen

Children all born Harrow on the Hill Middlesex

Mary        b 29 Aug 1810

James       b 15 Sep 1812

John         b 3 May 1814 (d. 6 June 1873, West Melbourne Victoria.)

Thomas    b 22 Jan 1816

William    b 24 Mar 1818

George     b 20 Apr 1820

Matilda     b 7 May 1822

Pamela     b 13 May 1824

Alfred      b 24 May 1827

Tabitha     b 16 May 1829

Emma       b 15 May 1831, d 26 Jul 1832

Arthur      b 2 Aug 1833

Emma       b 13 Jan 1836, d 5 Aug 1838

Graeme Goller's information is in brackets

View near Harrow on the Hill, spire of St Mary's Church visible in the distance. Francis Jukes, 1798Wikipedia "Harrow on the Hill formed an ancient parish and later civil parish in the Gore hundred of Middlesex.^[4] In 1831 it had a population of 3,861 and occupied an area of 9,870 acres (39.9 km²). "