Complex sentence: Ordered from the builders HM Dockyard, Devonport in December 1969, it was launched in March 1971 and at the time it was in operation it was primarily utilised by the Admiralty Underwater Weapons Establishment at Portland Naval Base.
Split into simpler sentences: Ordered from the builders HM Dockyard, Devonport in December 1969, it was launched in March 1971. At the time it was in operation it was primarily utilised by the Admiralty Underwater Weapons Establishment at Portland Naval Base.