Little is known of his life. In 1723, he was paid for a design for Holy Trinity Church, Leeds which was never executed, and his book "Practical Architecture" (1724) was dedicated to Yorkshire landowner and Member of Parliament Sir Thomas Frankland. "The Art of Sound Building" (1725) was dedicated to the Parliamentary official Sir Andrew Fountaine, and in 1726 he submitted a design for a bridge across the River Thames at Fulham. Batty Langley mentions him in his book "Ancient Masonry" (1736) as "Mr William Halfpenny, alias Hoare, lately of Richmond in Surrey, carpenter."