Complex sentence: Hussey's alledged great-great-great-grandfather was John Hussey, 1st Baron Hussey of Sleaford, by first marriage to Margaret Blount, who was beheaded by King Henry VIII in 1537 for treason.
Split into simpler sentences: Hussey's alledged great-great-great-grandfather was John Hussey, 1st Baron Hussey of Sleaford by his first marriage to Margaret Blount. Lord Hussey was beheaded by King Henry VIII in 1537 for treason.