Complex sentence: Protection of royal and diplomatic buildings in London was originally the responsibility of the Royalty Protection Division which was created in 1982 and absorbed the Royalty Protection Squad which had been created in the late 1970s.
Split into simpler sentences: Protection of royal and diplomatic buildings in London was originally the responsibility of the Royalty Protection Division which was created in 1982. Which also absorbed the Royalty Protection Squad, itself created in the late 1970s.