Covid-19: Defence secretary and military heads self-isolate Published image copyrightGetty Images image captionDefence Secretary Ben Wallace and Chief of the Defence Staff General Sir Nick Carter, pictured last year Defence Secretary Ben Wallace and six senior military commanders are self-isolating after the head of the armed forces tested positive for Covid-19. Mr Wallace and the heads of the Royal Navy, RAF and Strategic Command were contacted by the NHS Test and Trace app and told to stay at home for 10 days. They had come into contact with Chief of Defence Staff General Sir Nick Carter on Thursday. Military business will be conducted remotely.