For years I’ve “known” that ancestor William LILLEY married a lass called Margaret in the 1850s and I’m descended from their daughter Isabella LILLEY who was born about 1858 in Wallsend or Willington Quay.
However I could never find the marriage of Margaret & William nor the births of their first three daughters.
I now know that Margaret THOMPSON had three daughters before she married William in 1859 and what I would like to know is whether there are any records such as baptism which will give a clue as to the father of Isabella THOMPSON born 19 March 1858 in Willington.
Margaret may have had a long term relationship with William while he lived with his widowed mother or maybe she had a string of men – for fun or money.
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To avoid any waste of time chasing up things I already know I have listed below the relevant facts as I know them:

1841 census Ho107-827-2 folio 34, Cottages, Wallsend
Adam LILLEY 44 Waterman Y
Isabella do 44 Y
William do 18 Labourer Y
Isabella do 16 Y
Abraham do 14 Y
Adam do 12 Y
Nancy do 9 Y
Margaret do 9 Y
Thomas do 4 Y
George do 2 Y

Death certificate, sub-district Wallsend, says:
1st December 1845 Adam LILLEY, male, 46 years, Sailor, Found Drowned, Informant J REED Coroner Newcastle upon Tyne, registered 27 December 1845, Registrar Benjamin Forster.

1851 census Ho107-2409 folio 46, West Row, Wallsend [indexed as LIBY]
Isabell LILY Head Widow 49 NBL Berwick
William do Son U 27 Lab NBL do
Abram do Son U 23 Lab NBL do
Adam do Son U 21 Lab NBL do
Nancy do Daur U 18 NBL do
Margaret do Daur U 18 NBL do
Thomas do Son 14 Lab NBL do
George do Son 10 NBL Wallsend
Mary Ann do Gnd Child 11 mo NBL do [FreeBMD has birth Jun qtr 1850 Tynemouth 25 519 of Mary Ann LILLEY- cert says mother Margaret; no father]

Where Margaret THOMPSON was in 1851 I cannot pin down.

Birth Certificate - Born 2 January 1853 Willington Quay; Margaret; Girl; no father; mother Margaret THOMPSON; informant + The mark of Margaret THOMPSON Mother Willington Quay; registered 19 April 1853.
IGI has a birth:- Margaret Ellen THOMPSON 11 Mar 1854 St Peter's Wallsend NBL to Margaret THOMPSON (no father), batch I022077

Birth certificate - Sub-district Wallsend. Born 6 Sep 1855, Church Bank; Hannah; girl; father - blank; mother Margaret THOMPSON; informant X The mark of Margaret THOMPSON, Mother, Church Bank; registered 19 Sep 1855.

Birth Certificate 10b 101 Mar 1858 Tynemouth District, sub-district Wallsend:
19 March 1858, Willington; Isabella; Girl; no father; mother Margaret THOMPSON; informant Margaret THOMPSON of Willington; registered 23 March 1858.

Marriage Certificate - 9 April 1859 Parish Church Tynemouth by Banns. William LILLEY; full age; Bachelor; Miner; This Parish; father Adam LILLEY, Mariner. Margaret THOMPSON; full age; Spinster; This parish; no father. Witnesses: Abraham LILLEY, Jane WAUGH.

1861 census RG9-3781 folio 123, Six House Row, Monkwearmouth, Sunderland
William LILLEY Head Mar 37 Coal Miner Berwick-on-Tweed
Margaret do Wife Mar 33 NBL Bentley
Margaret do Daur 8 NBL Wallsend
Hannah do Daur 5 NBL do
Isabella do 3 NBL do

1861 census RG9-3781 folio 103, Corn Hill, Southwick, Sunderland
Isabella LILLY Head Widow 62 House Holder NBL Berwick
Then in same dwelling
John WOLLEY Head M 40 Labourer Ireland
Mary do Wife M 28 Ireland
Thomas do Son 2 DUR Southwick
new family in same dwelling
Joseph LAWLESS Head M 51 Labourer Ireland
Mary do Wife M 51 Ireland
and children born in Sunderland

Possible Death Index for Isabella LILLEY from FreeBMD:
Dec qtr 1865 Isabella LILLEY Sunderland 10a 288 ----- ORDERED 15 Feb 07 ----
Died 5th Nov 1865 Corn Hill Southwick; Isabella LILLEY; Female; 69 Years; Widow of Adam LILLEY, A Mariner; Sundry Infirmities of Old Age Certified; informant The Mark of William LILLEY Present at the death, Colliery, Monkwearmouth; registered 6th November 1865. (Age could be 67)

Death certificate Sunderland District, sub-district South Bishop Wearmouth vol 10a page 344.
Died 11 March 1869 Ryhope Pit, name William LILLEY Male 48 years Coal Miner Cause of Death Accidental fall of stone, Informant - Information received from Crofton MARWOOD Coroner for Easington Ward Durham. Inquest held 12 March 1869, registered 15 March 1869, Registrar Tho SWAN.

1871 Census RG10-5012 Folio 17v, 9 Bell Street, DUR Ryhope
Margaret LILLEY Head W 42 Mangle Woman NBL Benkley
Hannah do Daur UnM 15 Domestic Servant NBL Wallsend
Isabella do Daur 13 Scholar NBL do
William do Son 9 Scholar DUR Sunderland
Adam do Son 6 DUR do

Marriage Certificate 10a 832 - 21 July 1873 Sunderland Reg. Off.
Groom; John COPE 24 Bach. Coalminer; res. Ryhope; father Richard COPE Coalminer
Bride; Margaret Ellen LILLEY 19 Spinster; res. Ryhope; father William LILLEY Coalminer
Witnesses Timothy PAGET, Elizabeth HADDRICK

Deaths - Sep 1873 Hannah LILLEY age 17 Sunderland 10a 360
Died 2 Aug 1873, 66 Ryhope Street, Ryhope; Hannah LILLEY; Female; 17 years; Daughter of William LILLEY Coal Miner (deceased); Consumption; informant John COPE, present at the death, 66 Ryhope Street, Ryhope; registered 4 Aug 1873.

Marriage Certificate: 1877 at Registry Office Sunderland 26 May 1877
Groom: Robert MUSGROVE; age - 22; Bachelor; Coal Hewer; residence - 50 Railway Street Ryhope; Father Allen MUSGROVE, Coal Miner.
Bride: Isabella LILLEY; age - 21 years; Spinster; residence - 65 Ryhope Street Ryhope; father William LILLEY (deceased) Coal Miner.
Robert marked, Isabella signed
Witnesses: Stephen X Duck and Margaret Ann Duck