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The following I have found and may be of interest.
First name(s) James Gunn
Last name Sinclair
Birth year 1880
Birth date ? ? 1880
Baptism year 1880
Baptism date 08 Apr 1880
Father's first name(s) Alexander
Mother's first name(s) Julia Sophia
Parish St Barnabas, Pimlico
County Middlesex
Country England
Archive City of Westminster Archives Centre
Page 184
Record set Westminster Baptisms
Category Birth, Marriage, Death & Parish Records
Subcategory Parish Baptisms
Collections from England, Great Britain
https://www.findmypast.co.uk/transcript?id=GBPRS%2FB%2F491545509%2F1
Possibly the right Budge but not 100% certain
First name(s) Julia Sophia
Last name Budge
Gender Female
Birth year -
Birth place -
Baptism year 1835
Baptism date 29 May 1835
Place Topsham
County Devon
Country England
Father's first name(s) George
Father's last name Budge
Mother's first name(s) Sophia
Mother's last name -
Record set England Births & Baptisms 1538-1975
Category Birth, Marriage, Death & Parish Records
Subcategory Parish Baptisms
Collections from England, Great Britain
https://www.findmypast.co.uk/transcript?id=R_962238405
Marriage:
First name(s) Julia Sophia
Last name Budge
Age Full
Residence -
Marriage year 1866
Parish St Peter, Eaton Square, Pimlico
Spouse's first name(s) Alexander
Spouse's last name Sinclair
Spouse's age Full
Spouse residence -
County Middlesex
Country England
Archive City of Westminster Archives Centre
Record set Westminster Marriages
Category Birth, Marriage, Death & Parish Records
Subcategory Parish Marriages
Collections from England, Great Britain
https://www.findmypast.co.uk/transcript?id=GBPRS%2FM%2F492477551%2F2
Cheers, Rich