SImon Bartholomew Geoffrey Howard was 66 when he passed away in York Hospital on February 27 from what his family said were complications relating to his diabetes.
Inquests are held when a death is sudden, violent or unnatural and an opening into Mr Howard's will be held on March 30 at North Yorkshire Coroner's Court before being adjourned for a full hearing at a later date when an official cause of death will be ascertained.
Mr Howard had been in poor health and last year was found unfit to stand trial for historic sexual offences due to a brain injury suffered in a fall at his home in Norton, near Malton, in 2020.
He was discharged from York Crown Court but it was accepted that he had committed the indecent assuault against a girl in the Castle Howard gatehouse in 1984 during a trial of facts.A Castle Howard estate spokesman said: "We are able to confirm that very sadly, Simon Howard has died, following an ongoing illness and recent complications with his diabetes. We would ask for the family to be afforded privacy at this difficult time."
Mr Howard leaves his wife, Rebecca Sieff, and their twins, Octavia and Merlin, who are 20.
He was the third of four sons born to George Howard and took over from his father as custodian of Castle Howard, the stately home near Malton, in 1984. He ran the house for over 30 years, but in 2014 the management of the estate passed to his brother Nicholas following a disagreement. Their eldest brother, Henry, had died in 2008. Simon and his family moved to another property nearby.
He had also recovered from throat cancer in the past.
The house and estate are run by a company, Castle Howard Ltd, which had Simon and Nicholas as majority shareholders. Simon held the roles of chairman and managing director, and was credited with saving the stately home from the risk of being sold and turning it into a successful visitor attraction.
Rebecca Howard claimed in an interview with The Telegraph in 2018 that Nicholas' wife, former publishing boss Victoria Barnsley, had joined the board of Castle Howard and that soon after, Simon was asked to step down from his roles.
Nicholas' legal team later allegedly requested that Simon, Rebecca and their children leave Castle Howard, and they subsequently moved to Welham Hall. Rebecca claimed that the brothers remained on speaking terms.
He stepped down as a director and shareholder of the estate in 2016.
The Howards of Castle Howard are descended from a younger son of the ninth Earl of Carlisle.