Chai Patel, the former chief executive of the Priory Group, has sold the bulk of his remaining 16 per cent stake in the psychiatric hospital group in a move that is likely to quash long-running speculation that the doctor-turned-entrepreneur would partner a financial backer to buy the company.

Mr Patel, a one-time donor to the Labour party who was caught up in the “cash-for-honours” affair, is understood to have sold nearly all of his shareholding in the company earlier this month for 90p a share, delivering him a windfall of about £13.7m ($27.3m).