Complex sentence: During this period Holbrook married Frances Ann Bellhouse with whom he had 6 children, however in 1850 he was advised to retire due to ill health and left the business with Nasmyth.
Split into simpler sentences: During this period Holbrook married Frances Ann Bellhouse. In 1850 Gaskell he was advised to retire due to ill health and left the business with Nasmyth.