Maurice Regan, the US-based building tycoon, has filed a High Court action against billionaire racing boss John Magnier and his stud business, alleging they have breached competition law by barring Regan from using an equine hospital and Coolmore Stud. The legal action escalates the conflict between the two billionaires that began when they clashed in 2023 over rival bids for the Barne Estate farm outside Clonmel.