Baptised in Collingbourne Kingston, Wiltshire on 7 April 1668, he was the son of Richard Long of Collingbourne Kingston by his wife Elizabeth, daughter of Edward Long of Rood Ashton, Wiltshire.
He married Elizabeth, daughter of Thomas Long of Rowden, Chippenham.
After the election there was an allegation of fraud on the part of Long and his supporters, who, a Committee of Inquiry were told, had bribed and threatened certain voters in order to secure their vote.
The committee found that Firebrace's supporters had in fact bribed the witnesses to make false claims, and Long was exonerated.
As a supporter of the Immorality Bill he believed the remedy for poverty was the suppression of alehouses, "the most... intolerable grievance we have."