I have noticed that you imply William John and Janie Amy had children between 1882 and 1919. This must have been William John's parents! The current pair didn't marry until 1903. Something to sort out!

England & Wales, FreeBMD Birth Index, 1837-1915
Name: Janie Amy Dingle
Date of Registration: Jan-Feb-Mar 1882
Registration district: Bodmin
Inferred County: Cornwall
Volume: 5c
Page: 86

England, Select Births and Christenings, 1538-1975
Name: Jane Amy Dingle
Gender: Female
Baptism Date: 26 Mar 1882
Baptism Place: St. Minver, Cornwall, England
Father: John Dingle
Mother: Elizabeth Ann
FHL Film Number: 1596064
Reference ID: P 148 L 1155

England & Wales, FreeBMD Marriage Index, 1837-1915
Name: Janie Amy Dingle
Date of Registration: Jan-Feb-Mar 1903
Registration district: Penzance
Inferred County: Cornwall
Volume Number: 5c
Page Number: 356
Spouse's Name William John Sincock

1911 England Census
Name: William John Sincock
Age in 1911: 27
Estimated birth year: abt 1884
Relation to Head: Head
Gender: Male
Birth Place: Cornwall
Civil Parish: Penzance
County/Island: Cornwall
Country: England
Street address: 16 Buriton Row, Penzance, Cornwall
Marital Status: Married
Occupation: Town Porter

William John Sincock 27
Janie Amy Sincock 29
William John Sincock 7
Janie Amy Dingle Sincock 6
Regenild Charles Sincock 5
Elfreda Maud Sincock 3
Garfield James Sincock 1

Other Children after 1911 census:

Name CHARLES C SINCOCK
Mother's Maiden Name DINGLE
Year 1914

Name FRANK D SINCOCK
Mother's Maiden Name DINGLE
Year 1911

Name IVY L SINCOCK
Mother's Maiden Name DINGLE
Year 1916

Name LEONARD R SINCOCK
Mother's Maiden Name DINGLE
Year 1919

Name Albert R Sincock
Mother's Maiden Name: Dingle
Year 1913

http://www.cornwall-opc-database.org/
Marriage
Day Month 18-Feb
Year 1903
Parish Or Reg District Ives, St.
Groom Fn William John
Groom Sn SINCOCK
Groom Age 20
Groom Residence Gabriel Street
Groom Condition Bachelor
Groom Rank Profession Boots at Hotel
Groom Signed / Marked (S/M) S
Groom Father Name William John
Groom Father Rank Profession Naval Pensioner
Bride Fn Janie Amy
Bride Sn DINGLE
Bride Age 21
Bride Residence Gabriel Street
Bride Condition Spinster
Bride Rank Profession
Bride Signed / Marked (S/M) S
Bride Father Name John
Bride Father Rank Profession Farm Labourer
Banns / Licence (B/L) B
Witness Fn1 Thomas
Witness Sn1 Dingle
Witness Fn2 Elizabeth
Witness Sn2 Sincock

Transcriber T Bowler

1891 England Census
Name: William John Sincock
Age: 7
Estimated birth year: abt 1884
Relation: Son
Father's Name: William Sincock
Mother's name: Eliza Jane Sincock
Gender: Male
Where born: Penzance, Cornwall, England
Civil Parish: Penzance
Ecclesiastical parish: St Mary
Town: Penzance
County/Island: Cornwall
Country: England
Street address: 3 Custom House Lane
Occupation: Dock labourer (father)

William Sincock 34 b Truro Cornwall
Eliza Jane Sincock 36 Penzance, Cornwall
Elizabeth Sincock 11 Penzance, Cornwall
William John Sincock 7 Penzance, Cornwall
Albert Sincock 6 Penzance, Cornwall
Alfred Sincock 2 Penzance, Cornwall
Charles James Sincock 2/12 Penzance, Cornwall

http://www.cornwall-opc-database.org/
Marriages database
Day Month 08-Jun
Year 1879
Parish Or Reg District Penzance, St. Mary
Groom Fn William
Groom Sn SINCOCK
Groom Age full age
Groom Residence New Street
Groom Condition bachelor
Groom Rank Profession mariner
Groom Signed / Marked (S/M) S
Groom Father Name John
Groom Father Rank Profession confectioner
Bride Fn Eliza Jane
Bride Sn ROWE
Bride Age full age
Bride Residence New Street
Bride Condition spinster
Bride Rank Profession
Bride Signed / Marked (S/M) S
Bride Father Name John
Bride Father Rank Profession labourer
Banns / Licence (B/L) B
Witness Fn1 Susan
Witness Sn1 Wallis
Witness Fn2 John
Witness Sn2 Try (mark)

Transcriber Susan Evans Shaw

England & Wales, FreeBMD Birth Index, 1837-1915
Name: William John Sincock
Date of Registration: Jul-Aug-Sep 1883
Registration district: Penzance
Inferred County: Cornwall
Volume: 5c
Page: 244


1891 England Census
Name: Janie A Dingle
Age: 9
Estimated birth year: abt 1882
Relation: Daughter
Father's Name: John Dingle
Mother's name: Elizabeth Dingle
Gender: Female
Where born: St Minver, Cornwall, England
Civil Parish: St Minver Lowlands
Town: Penmayne
County/Island: Cornwall
Country: England
Occupation: Farm labourer (father)

John Dingle 36
Elizabeth Dingle 39
John Dingle 14
Mary E Dingle 11
Janie A Dingle 9
Thomas Dingle 7
William J Dingle 4
Susannah Dingle 2


http://www.cornwall-opc-database.org/
Marriages database
Day Month 05-Apr
Year 1876
Parish Or Reg District Minver, St.
Groom Fn John
Groom Sn DINGLE
Groom Age full age
Groom Residence St Minver, Stoptide
Groom Condition bachelor
Groom Rank Profession labourer
Groom Signed / Marked (S/M) M
Groom Father Name William Dingle
Groom Father Rank Profession labourer
Bride Fn Elizabeth Ann
Bride Sn ARNY
Bride Age full age
Bride Residence St Minver, Porthilly
Bride Condition spinster
Bride Rank Profession servant
Bride Signed / Marked (S/M) S
Bride Father Name John
Bride Father Rank Profession labourer
Banns / Licence (B/L) BANNS
Witness Fn1 John Arny
Witness Sn1 Hora
Witness Fn2 Mary
Witness Sn2 Bird *
Transcriber Notes Surname of Mary Bird is probably BURT*
Transcriber Pat Balmer