L ondon fintech WorldFirst has seen a mass board exodus as billionaire Jack Ma tightens his grip on the management of the payments company, the Standard has learnt. A suite of senior leaders have left the firm over the past year, including its CEO, finance director, managing director and UK country manager. Senior members of the company’s risk and legal team have also left, including its head of risk, chief information security officer, and group general counsel and compliance officer. Staff at the fintech’s parent company, Ant Financial, as well as its sister company, Chinese payments platform Alipay, have been…