Eton-educated Simon, 65, is the third of four sons born to his late father George Howard, Baron Henderskelfe, who died in 1984 - the same year the offences are alleged to have taken place.
The eldest brother, Henry, suffered health problems and died in 2008, aged 58. The second, Nicholas, turned down the chance to run the estate as a young man, opting instead to pursue a career in music and later photography. Instead, Simon took over the reins from their father, and began managing Castle Howard in 1983. The same year, he married his first wife Annette Smallwood, whom he divorced in 2000.
He married his current wife, Rebecca Sieff, a year later and they have 19-year-old twins together.
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, a nearby property. Rebecca claimed that the brothers remained on speaking terms.
Simon, who served as High Sheriff of North Yorkshire in the 1990s, will appear at Scarborough Magistrates' Court next week.
A statement from his family said that he was initially interviewed about the allegations in 2018, and has now been charged under the Sexual Offences Act with counts of indecent assault and incitement to commit an act of gross indecency relating to an incident at his home in 1984.
The statement added that the family were 'shocked' by the allegations and that Simon strongly denies them.
He stepped down as a director and shareholder of the estate five years ago.
The Howards of Castle Howard are descended from a younger son of the ninth Earl of Carlisle.