Deydras, who was working as a clerk in Oxford at the time, did apparently bear a striking resemblance to the current King, Edward II. He was equally as strong and tall as the king, but Deydras was missing an ear.

This missing ear, he claimed, was the key to understanding his claim to the throne. Deydras claimed that while he was a baby a careless servant had allowed him to be savaged by a sow. The sow bit off his ear, and the horrified servant was so afraid of the punishment she would receive for her neglect that she swapped the royal baby (Deydras) with the baby of another servant and managed to successfully pass this low-born baby off as the son of Edward I. The servant's subterfuge was never found out and the swapped baby was raised to be King, while Deydras, the true heir to the throne, was raised in poverty.

According to the Lanercost Chronicle, Deydras "declared that my Lord Edward was not of the blood royal, nor had any right to the realm, which he offered to prove by combat to him". A risky claim to make to say the least!

Despite the seeming implausibility of Deydras's claims, as word of them spread they did begin to gain some traction. Edward II was not a universally popular king, having lost the Battle of Bannockburn, feuded with his cousins, and alienated the Barons. His interest in the life of the common man had also been commented on, particularly his interest in such 'low' occupations as thatching and ditch-digging. Could this be a sign that Edward II was truly a changeling, a commoner in disguise?

It appears that Edward II did not take Deydras's claims at all seriously. When Deydras was brought before him at the Northampton parliament in August, the King jokingly greeted him with "Welcome, my brother!" and suggested that Deydras could be kept around to act as a court jester.

Edward II's wife Isabella, however, did not see the funny side. Whether she saw Deydras as a genuine threat to her husband's legitimacy, or merely a public embarrassment, is not clear. What is clear is the result, John Deydras was charged with sedition and thrown into prison.

At Deydras's trial, his story took an even more bizarre turn. Under questioning, Deydras admitted that the whole story was a fabrication, put pointed the finger of blame squarely at his pet cat!

He claimed that the Devil had started speaking to him through the cat one day whilst he was walking across Christchurch meadow. He claimed that it was the Devil-cat who had encouraged him to make his fantastical claims.

The idea of the Devil speaking through a cat may seem crazy today, but in the 14th century, with rumours of witchcraft abounding in Europe, the authorities were not taking any chances. Deydras was hanged at Northampton, and his cat was hanged beside him!

A sad end for what was clearly a deeply troubled young man (and an innocent cat), though an end that was definitely preferable to the death rumoured to have been experienced by Edward II himself!

John Deydras's story of being savaged a sow may seem far-fetched today, but during the 14th-century the average person mingled with farm animals in their daily lives far more than we do today, and tragedies did occur as a result.

In Oxford in 1392, six-month old Agnes Perone was killed and partially eaten by a sow. The pig was then arrested. This may sound strange but the practice of arresting and putting animals like pigs to trial for crimes against humans was not unheard of during this period.

The practice was more common in France, with famous cases including that of Perrinot Muet, a young swineherd who was killed by three sows in his charge, and that of an infant from Falaise who was killed and eaten by a pig. In both cases the pigs were tried and sentenced to death.

The idea that domestic pigs could be a threat to life (and in particular infant life) was so widespread in 14th century England that it featured in Geoffrey Chaucer's 'The Knight's Tale', which refers to:

With this climate of fear about pig attacks so prevalent in England, perhaps John Deydras's story wasn't so outlandish after all?