Speaking as a not-so-humble Continuing Airworthiness Management Engineer: There are no Emergency Airworthiness Directives from the CAA for either the Spitfire or Hurricane aircraft, nor the Merlin engine - so civilian Spitfires and Hurricanes are not grounded. Why all the secrecy? If the Royal Air Force are aware of an airworthiness problem that justifies grounding their fleet, their duty on safety grounds is to share that information with all operators of the same type. Is it a due to (heaven forbid) a "Maintenance Error" within the BBMF? Have they for example, overrun a scheduled or mandatory inspection?