Who killed the valet of the ‘deeply unpleasant’ Duke of Cumberland? The Mail’s Robert Hardman and historian Kate Williams explore in new podcast how the hated royal was attacked – before his aide was found with his throat cut

He was disliked by his father and siblings and was unpopular with the public.

So it is perhaps not surprising that, when the valet of the Duke of Cumberland was found dead in his room at St James’s Palace with his head partially severed, an element of suspicion fell on him.

But the death of Thomas Sellis on May 31, 1810, was implausibly ruled a suicide at an inquest, leaving the Duke – the reviled fifth son of King George III – off the hook.

Now, the mystery of who killed Sellis is explored in the eighth episode of new Daily Mail podcast Queens, Kings and Dastardly Things.

Mail columnist and royal biographer Robert Hardman and his co-presenter Professor Kate Williams examine whether the Duke himself might have murdered the popular Sellis. 

They explore how, just hours before Sellis’s body was found, the Duke was attacked while he was asleep in his apartments, prompting him to cry, ‘I murdered! I murdered!’, and call for the help of his other valet, Cornelius Neil. 

They also investigate the claim that Sellis attacked the Duke and then took his own life after failing to kill him. 

Listen to the full episode now: 

A cartoon depicting the Duke of Cumberland being attacked by his valet in 1810 

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Mr Hardman says of the Duke: ‘He’s quite an accomplished soldier, but he’s also a deeply unpleasant man, isn’t he? 

‘He has a certain notoriety around him. Out of all of George III’s rather naughty and disliked sons, he is the most disliked.

The historian added: ‘He’s seen as very creepy, his sisters don’t like him, they find him very strange, and he’s generally unpopular. 

‘He is against reform, which means expanding the vote, and he lives on public money. 

‘He’s someone who is very much disliked by the public and disliked in private life as well.’

The Duke claimed that, around an hour after going to bed, he was woken up with a bang on the head. 

He was then slashed on the leg by an assailant as he attempted to flee, prompting him to cry out. 

Neil came running to his aide, and the pair allegedly set off after the assailant.

A search of the Duke’s room found a pair of slippers belonging to Sellis. Also found was the Duke’s sword, which was covered in blood.

But the valet himself could not be found.

On going to his room, they found him lying in a pool of his own blood. 

His throat had been slashed so deeply that his spine had stopped the blade. The wash basin meanwhile was half full of bloody water.

The Duke of Cumberland was sleeping in St James’s Palace when he was attacked. Hours later, Joseph Sellis was found dead in his room. His throat had been cut with a razor

Professor Williams says: ‘His head is nearly severed from his body. Now that is some razor. There’s blood. Everywhere, all over the furniture, the floor, the corridor. 

‘And by this point, the searchers have trodden the blood all over the place. 

‘The wash basin is half full of bloody water. I’m sure Agatha Christie would have a field day here, or certainly Hercule Poirot would.’ 

Sellis was born in Corsica and had lived in New York before starting as a royal valet.

He had been in the service of the Duke of Cumberland for five years when he was killed. 

According to Professor Williams, he was ‘very popular’, including with the Duke himself. 

At an inquest into his death, the Duke’s other valet, Cornelius Neil, said he believed Sellis was trying to murder his boss and then frame him for the killing.

The inquest concluded that Sellis had tried and failed to murder the Duke and so had returned to his own room to take his own life.

It also emerged that Sellis had been accused of theft in New York by a previous employer, who fired him. 

Sellis was also found to be a strong supporter of American independence and a critic at the time of King George III.

At the time, Sellis’s death was a newspaper sensation. 

Members of the public were even allowed to enter St James’s Palace to see the crime scene, where Sellis’s blood was still visible. 

The Duke of Cumberland was the fifth son of King George III

Those interested in the case failed to understand how, if Sellis really had tried to take the Duke’s life, how he failed to kill him when he was asleep. 

Some believe that the Duke may have been having a sexual affair with Neil, and that Sellis could have been murdered because he was about to expose it. 

A book making this claim was published several years after Sellis’s killing, prompting the Duke to take libel action in court. 

Although he won the case, he could never shake the perception among many that he was responsible for Sellis’s death 

So what is the verdict of Professor Williams and Mr Hardman?

Listen to the eighth episode of Queens, Kings and Dastardly Things now to find out. 

Elizabeth II and Charles III: New King. New Court. The Inside Story. 

Professor Kate Williams is the author of the recent book The Royal Palaces: Secrets and Scandals, along with many other works.