Complex sentence: He served as First Sea Lord and Chief of the Naval Staff in the mid 1970s and in that role he advised the incoming Labour Government on a major defence review and on the implications of the Turkish invasion of Cyprus.
Split into simpler sentences: He served as First Sea Lord and Chief of the Naval Staff in the mid 1970s. In that capacity he advised the incoming Labour Government on a major defence review and on the implications of the Turkish invasion of Cyprus.