Complex sentence: In 1975, the civic offices moved out of the Town Hall to Reading Civic Centre and they were followed in 1985 by the Reading Central Library, leaving only the museum and concert hall in use.
Split into simpler sentences: In 1975, the civic offices moved out of the Town Hall to Reading Civic Centre. They were followed in 1985 by the Reading Central Library which left only the museum and the concert hall in use.