Complex sentence: Decommissioned in 1854, the castle was first leased, and later bought outright, by the Royal Yacht Squadron to form their new clubhouse, who then employed Anthony Salvin to rebuild large parts of it between 1856 and 1858.
Split into simpler sentences: Decommissioned in 1854, the castle was first leased, and later bought outright, by the Royal Yacht Squadron to form their new clubhouse. The Squadron then employed Anthony Salvin to rebuild large parts of it between 1856 and 1858.