I am sure you have checked all Holmes in the area but just in case
Harriet Ann Holmes married Mark Gilbert in 1858 - marriage not yet on IG.
Sarah Holmes, Shanbally, grandmother was informant on birth of child Robert Frederick, 1865 and William in 1867.
Sarah Holmes, Shanbally, widow of a Coachman died 1891 informant William Gilbert
Robert Holmes, Shanbally, servant died 1879.
If Robert and Sarah are your William’s parents, he looks to have a sister coincidentally called Harriet Ann.
A coachman and a servant do not match ‘clerk’ though
