This is not the original gibbet, but a reconstruction from around 1900 which used to stand outside the now disappeared inn of the same name. Rather than a traditional gallows, used for hanging, the gibbet was an altogether more macabre punishment.
"Gibbeting was the punishment for some capital offences including highway robbery. An iron cage would have hung from the wooden arm of the original gibbet. Here criminals were hung, imprisoned in the cage until they were dead. The head was clamped at the top to prevent tired legs from resting and the person would slowly starve to death, or in the winter succumb to exposure. The body would remain suspended for some time after death as a warning to others.". (Source: cprs.org.uk)
There are no primary sources indicating that the death penalty was actually carried out at Caxton. It seems that as Caxton had one of the only two post offices in the country, there would have been a high incidence of highway robbery. Local Antiquarian, William Cole (1714-1782) is believed to have referred to Caxton when he wrote this:
"About 1753 or 1754 the son of Mrs. Gatward being convicted of robbing the Mail was hanged in chains on the Great Road. I saw him hanging in a scarlet coat after he had hung 2 or 4 months it is supposed that the screw was filed which supported him and that he fell in the first high wind after."
This site in Caxton is shortly going to become a MacDonald's. Some would prefer the gibbet.