Brandon was born in London, at an unknown date, son to the common executioner of London, Gregory Brandon, and his wife Alice. Gregory Brandon had become executioner in 1611, and was then living with his family on Rosemary Lane, Whitechapel (now known as Royal Mint Street). Though little can be ascertained of Brandon's early years, rumours abounded of his gruesome upbringing as the son of London's executioner. He was rumoured to have decapitated stray cats and dogs, in training for his future position. Brandon's father, Gregory, found himself on the wrong side of the law in January 1611, when he was convicted of the manslaughter of one Simon Morton, though he was not punished thanks to a bizarre pleading of the benefit of clergy. In 1617 Gregory was the butt of a practical joke played by the members of the London College of Arms, wherein he was granted "the royal arms of Arragon, with a canton of Brabant" and thereby made into a gentleman. This joke was taken up by the people of London, who elevated Gregory to esquire, a satirical title that passed down to his successors as London's hangman. This resulted in the imprisonment of the members responsible, including the Garter Principal King of Arms, William Segar.