Complex sentence: George Drummond took over when Peter Redpath retired in 1888 and under his guidance, the company's success allowed for construction of a new six-storey plant built on the existing site that doubled production capacity.
Split into simpler sentences: George Drummond took over when Peter Redpath retired in 1888. Under his guidance, the company's success allowed for construction of a new six-storey plant built on the existing site, doubling production capacity.