Complex sentence: William Collins publishers bought the firm of Geoffrey Bles in 1953 and Bles retired within a year or two but books continued to be published under the Bles imprint into the 1970s.
Split into simpler sentences: William Collins publishers bought the firm of Geoffrey Bles in 1953 and Bles retired within a year or two. Books continued to be published under the Bles imprint into the 1970s.