Complex sentence: The paper consolidated its centre-left stance during the 1970s and 1980s but was both shocked and revitalised by the launch of "The Independent" in 1986 which competed for a similar readership and provoked the entire broadsheet industry into a fight for circulation.
Split into simpler sentences: The paper consolidated its centre-left stance during the 1970s and 1980s. It was both shocked and revitalised by the launch of "The Independent" in 1986 which competed for a similar readership and provoked the entire broadsheet industry into a fight for circulation.