First given name from baptism record of son, Sidney James Wilson, found in October 2023:
Father: Frederick Thomas Wilson
Mother: Florence Wilson

Initial of “M” for second given name, age, place of birth, estimated year of birth, from the 1891 England Census taken on the night of 5 April 1891 for the Civil parish of Sheffield, Essex, England, found in October 2023:
House: Middleton Hall Lane
Frederick Wilson, Head, Married, age 25, Brewers Assistant, Born Brentwood Essex England [circa 1866]
Florence M Wilson, Wife, Married, age 24, Born Maldon Essex England [circa 1867]
Sidney Wilson, Son, Single, age 4, Born Maldon Essex England [circa 1887]
Thomas Wilson, Son, age 2, Born Sheffield Essex England [circa 1889]

Entry from the 1901 England Census taken on the night of 31 March 1901 for the Civil parish of Brentwood, Essex, England, found in October 2023:
House: Railway Square
Frederick Wilson, Head, Married, age 35, Brewers Assistant, Born Brentwood Essex England [circa 1866]
Florence M Wilson, Wife, Married, age 35, Born Maldon Essex England [circa 1866]
Sidney Wilson, Son, Single, age 14, Page Boy, Worker, Born Maldon Essex England [circa 1887]
Thomas Wilson, Son, age 12, Born Brentwood Essex England [circa 1889]
Daisy M Wilson, Daughter, age 4, Born Brentwood Essex England [circa 1897]
May Wilson, Daughter, age 2, Born Brentwood Essex England [circa 1899]