Complex sentence: On the south side of the street, there have been proposals for an office-to-residential conversion of Royal Sovereign House, which in 1980-81 was part of a development incorporating a supermarket and a five-storey office block.
Split into simpler sentences: On the south side of the street, there has been a proposal for an office-to-residential conversion of Royal Sovereign House. Built in 1980-81, this was part of a development incorporating a supermarket and a five-storey office block.