Thanks to the "New Boston Eye" for providing me with this story. Sibsey is a village best remembered as the birthplace of Old Mother Riley but it is also remembered for things not quite so pleasant.
On 18 March 1859, Henry Carey (aged 24) and William Pickett (aged 20) were drinking with William Stevenson in the Ship Inn at Sibsey Northlands, a small village 4 or 5 miles from Boston. When William Stevenson left the Inn to walk home, Carey and Pickett followed him. They Killed him and robbed him. The song says that they hit him so hard that his skull caved in.
Carey and Pickett were both arrested the following day. Their trial, at Lincoln Castle, lasted just over a day and they were soon found guilty and sentenced to death. On 5 August 1859, Carey and Pickett were hung by the executioner William Marwood. These were the last two public hangings in Lincoln Castle.
The song below, although not what you would call poetic, is included for the purpose of providing an example of the content of Lincolnshire's Broadside ballads.
UPDATE. I have since received an e-mail from Richard Brothwell (whose 2x Great Uncle was Henry Carey) who has researched this subject a lot and he says that The hangman was Thomas Askern not William Marwood. Thank you for that.