RIYADH: Saudi Arabia’s Crown Prince Mohammed bin Salman called Britain’s Prince Charles on Thursday to check up on him after his self-isolation period came to an end recently after testing positive for coronavirus. The British heir-to-the-throne ended his quarantine period on Monday and is in good health.  Last week, his Clarence House office revealed that Prince Charles, 71, had been tested after displaying mild symptoms of the virus and had spent a period of seven days in self-isolation at his Birkhall home in Scotland where he had continued to work.