In 1630, Castlehaven was publicly accused of raping his wife and committing sodomy with two of his servants. Castlehaven's son, James, claimed that it was the extent of Castlehaven's "uxoriousness" toward his male favourites which led to his initial lodging of a complaint. At a trial by his peers, it was stated that one such favourite, Henry Skipwith, had arrived at Fonthill Gifford in 1621 and that within a few years he was so close to Castlehaven that he sat at the family's table and was to be addressed as "Mister Skipwith" by the servants. Several years later, Giles Broadway arrived at the house and received similar treatment. It was not long before Castlehaven was providing Skipwith with an annual pension, and he was accused of attempting to have Skipwith inseminate his daughter-in-law, to produce an heir from Skipwith instead of his son. In fact, the countess and Skipwith had an adulterous relationship. Charges were brought against Castlehaven on the complaint of his eldest son and heir, who feared disinheritance, and were heard by the Privy Council under the direction of Thomas Coventry, Lord High Steward. Lady Castlehaven gave evidence of a household which she said was infested with debauchery, and the Attorney-General acting for the prosecution explained to the court that Castlehaven had become ill because "he believed not God", an impiety which made Castlehaven unsafe. However, he insisted he was not guilty and that his wife and son had conspired together in an attempt to commit judicial murder. All witnesses against Castlehaven would gain materially by his death and "News writers throughout England and as far away as Massachusetts Bay speculated about the outcome." Castlehaven maintained his innocence, and the trial aroused considerable public debate, After some deliberation the Privy Council returned a unanimous verdict of guilty on the charge of rape. The sodomy charge was also upheld, but by a slim margin as not all jurors agreed that actual penetration had taken place. The case remains of interest to some as an early trial concerning male homosexuality, but ultimately its greatest influence proved to be as a precedent in spousal rights, as it became the leading case establishing an injured wife's right to testify against her husband. Castlehaven was convicted, attainted, and three weeks later beheaded on Tower Hill for his sexual crimes: namely the "unnatural crime" of sodomy, committed with his page Laurence FitzPatrick, who confessed to the crime and was executed; and assisting Giles Browning, who was also executed, in the rape of his wife Anne, Countess of Castlehaven, in which Lord Castlehaven was found to have participated by restraining her. The page who was executed, Laurence FitzPatrick, testified that Lady Castlehaven "was the wickedest woman in the world, and had more to answer for than any woman that lived". In The Complete Peerage, Cokayne adds that the death of Castlehaven was certainly brought about by his wife's manipulations and that her undoubted adultery with one Ampthill and with Henry Skipwith renders her motives suspicious. According to the historian Cynthia B. Herrup, Anne was the equal of Lord Castlehaven in immorality. Under the terms of the attainder, Castlehaven forfeited his English barony of Audley, created for heirs general, but retained his Irish earldom and barony since it was an entailed honour protected by the statute De Donis. When he was beheaded on Tower Hill on 14 May 1631, those Irish titles passed to his son James.
Children
Mervyn Touchet's first marriage was with Elizabeth Barnham, daughter of London alderman Benedict Barnham and his wife, Dorothea Smith, and they had six surviving children:
