Complex sentence: In around 1822, he commissioned Sir Robert Smirke to remodel the house, and it was enlarged by Smirke's brother, Sydney, in 1839, but in 1850 a fire destroyed much of the property, including most of the Smirkes' work.
Split into simpler sentences: In around 1822, he commissioned Sir Robert Smirke to remodel the house, and it was enlarged by Smirke's brother, Sydney, in 1839. In 1850 a fire destroyed much of the property, including most of the Smirkes' work.