Admiral Sir Michael Boyce GCB OBE ADC Chief of Defence Staff Bronze Medallion.A Bronze Medallion presented by Admiral Sir Michael Boyce GCB OBE ADC Chief of Defence Staff. Admiral Sir Michael Boyce GCB OBE ADC (1943 2022) served as Chief of the Defence Staff from 2001 until 2003. This role is the professional head of the British Armed Forces, as well as the most senior uniformed military adviser to the Prime Minister and the Defence Minister. Admiral Boyce commanded three submarines and a frigate before achieving higher command