In 1871 the first royal in living memory gave evidence in court - and led to his lover spending the rest of her life in an asylum.
Edward, known as Bertie, was the then Prince of Wales who later became King Edward VII, and stood in the dock to discuss his relationship with his close friend, Harriet Mordaunt.
She had claimed to her husband she had broken her wedding vows with the eldest son of Queen Victoria, as well as other men, leading to him filing for divorce.
Harriet and the playboy prince had become friends when she joined him and the Princess of Wales in 1865 at Sandringham when she was 17-years-old.
When she married Sir Charles Mordaunt he presented her with a diamond and emerald horseshoe ring.
Once wed, she continued to see the prince despite her husband attempting to put an end to their relationship by forbidding them from seeing each other.
When he was away Harriet was often seen with the prince, including at her own home where her suspicious servants kept diaries of her dalliances.
In a shocking incident 18 months after their wedding, Sir Charles returned home from a trip early to find the prince on the doorstep of his home, Walton House in Warwickshire.
On the front lawn was his wife enjoying a carriage pulled by ponies which were gifts from her royal admirer.
Sir Charles demanded her visitor leave - before shooting the ponies dead.
Eight months later Harriet gave birth to a daughter and fearing she had passed on syphilis confessed to having affairs with the prince - as well as other men.
She told him she had been “wicked, often and in open day”.
In Harriet’s desk he found 18 letters from the prince, as well as a lock of his hair and flowers.
In court her father, Sir Thomas Moncrieffe, declared his daughter insane in an attempt to stop the divorce from happening.
Among those to give evidence at a pre-trial hearing was the prince who denied the affair.
After also hearing from several doctors - said to be friendly with the prince - she was eventually declared insane and Mordaunt’s divorce case fell.
Two years later Harriet was declared permanently insane and sent to an asylum where she spent the rest of her life until she died 33 years later in 1906.
Sir Charles eventually got his divorce when it was confirmed his wife would not recover and the prince became king in 1902 and died aged 68 in 1910.
