He was the owner of the William Clendinneng & Son Company (Limited), one of Canada's most important foundries, in operation from 1868 to 1904.

Born in Cavan, William Clendinneng arrived in Montreal with his family in 1847, at the young age of 14.

[1] Clendinneng joined the William Rodden & Company foundry (est.1810) located at Griffintown, near the Lachine canal, Montréal.

By 1886, the foundry's 450 workers made castings of all types, including: architectural and ornamental ironwork; agricultural and railway castings; drain and gas pipes; stoves, ranges, furnaces, and hollow ware; and household goods—the tools of the homestead farms and Canada's urbanization.

Clendinneng was a dedicated Methodist and a founding member and president of the Irish Protestant Benevolent Society of Montréal (est.