Complex sentence: Until 1980 she was known as HMS Clyde (the traditional name for ships attached to HMS Graham) however from that year naming policy with regard to ships allocated to RNR Divisions changed and she reverted her own name during this period.
Split into simpler sentences: Until 1980 she was known as HMS "Clyde" (the traditional name for ships attached to HMS "Graham"). However from that year naming policy with regard to ships allocated to RNR Divisions changed and she reverted her own name during this period.