During sentencing at Oxford Crown Court on Friday, Judge Ian Pringle KC described it a “bold and brazen” heist that took “no more than five-and-a-half minutes to complete”.

It happened just days after the artwork, entitled America and that was part of an exhibition by the Italian conceptual artist Maurizio Cattelan, went on show.

Sheen was a key player – a career criminal and the only man convicted of both burglary and selling the gold.

He pleaded guilty last year after police found his DNA at the scene and gold fragments in his clothing.

Police also recovered his phone that contained a wealth of incriminating messages.

Shan Saunders, the senior crown prosecutor on the case, said it was “unusual to have a phone that when downloaded contains so much information”.

During the trial, jurors heard voice messages sent by Sheen to Fred Doe, a Berkshire businessman who was convicted for conspiring to sell the gold in March.

Saunders said interpreting the messages was “a long and complicated process”, due to the blend of coded language, Romany slang and Cockney rhyming slang used.

In one message, Sheen confirmed he was in possession of some of the gold toilet.

It read: “I think you know what I’ve got… I’ve just been a bit quiet with it.”

He also used the word “car” as code for gold.

“ The car is what it is mate, innit? The car is as good as money,” he said.

Within two weeks of the heist Sheen had sold 20kg (44lb) of gold – about one fifth of the toilet’s weight – to an unknown buyer in Birmingham for £520,000.

A BBC investigation in March revealed Sheen’s criminal history.

It found he had been jailed at least six times since 2005 and led organised crime groups that had made more than £5m from fraud and theft – money that authorities had largely failed to recover.

There was no reaction from either of the men when their sentences were read out.

Sentencing Sheen, Judge Pringle said he had a “truly shocking list of previous convictions”.

Speaking directly to Sheen, he said: “You were almost certainly the figure who carried the sledgehammer on which your DNA was found and which was used to sever the functioning toilet from its connecting pipes.”

Sheen was already serving a 19-year sentence for previous crimes, and he will serve the four-year sentence for the heist consecutively.

The judge said Jones, who worked for Sheen as a roofer, also had a “long and unenviable list of previous convictions”.

In the week leading up to the heist he paid two visits to Blenheim.

Just a day prior to the raid, on Sheen’s instructions, he booked a timeslot on Blenheim’s website to use the gold toilet.

While inside the cubicle, Jones snapped pictures of the golden toilet and a lock on the door.

In one of the trial’s lighter moments he confirmed he did use toilet, calling the experience “splendid”.

“Your role was to carry out a reconnaissance of the museum, to know exactly where the golden toilet was situated and to work out the quickest route in and out of the palace, I have absolutely no doubt whatsoever,” Judge Pringle told Jones.

Speaking after sentencing, Det Supt Bruce Riddell, of Thames Valley Police (TVP), described Sheen as the “driving force behind the burglary, with his motive to make money by any means necessary”.

“Jones also played a key part in the burglary, as he carried out two recces at Blenheim Palace in the days leading up to the burglary, and it is our belief that he also was there on the night,” he continued.

Shan Saunders, for the Crown Prosecution Service (CPS), described it as an “extraordinary case” and “audacious theft”.

“However, given the level of planning… it was unusual that the offenders left such a trail of evidence in their wake,” she added.

“From phone messages to DNA traces found in a stolen car and on the sledgehammer used in the burglary, this wealth of evidence ultimately enabled us to secure their convictions.”

She said the CPS had reviewed 30,000 pages of evidence.

In October 2019, just one month after the heist, police arrested Sheen and Jones but they were subsequently released. They were not charged for another four years.

Det Supt Riddell said: “We arrested 12 people in total in the investigation, and that brings with it a huge amount of digital devices to examine.”

He also said it took months for key forensic evidence to be identified and that the investigation was slowed by the pandemic.

The BBC asked the probation service why Sheen was not recalled to prison in October 2019.

The Ministry of Justice said an arrest did not necessarily mean the offender had breached their licence conditions, and that Sheen was recalled to prison in May 2020 as soon as there was evidence he had done so.

Sheen has remained in prison since May 2020.

Five men were seen on CCTV carrying out the heist but it remains unclear whether Jones was actually at the raid, meaning either three or four burglars remain at large.

Det Supt Riddell said he was “fairly certain” officers knew who two of the other burglars were.

Only four of the 12 people arrested met the evidential threshold to bring charges, according to the CPS.

Det Supt Riddell said police were reviewing the case and appealed for anyone with information about the heist to contact TVP.

“I am aware that over the passage of time allegiances may change and it might be that someone out there has that one piece of evidence that may assist us in bring others to justice,” he said.

Doe, from Windsor, Berkshire, was found guilty of conspiring to sell the gold and given a 21-month suspended sentence in May.

Bora Guccuk, a jeweller from London, was cleared of the same charge at trial.