Complex sentence: By 1790 he had set up in business in London with financial backing from well-to-do currier John Maberly, where he designed a new steam engine based on the patented designs of Isaac Mainwaring.
Split into simpler sentences: By 1790 he had set up in business in London with finacial backing from well-to-do currier John Maberly. He designed a new steam engine based on the patented designs of Isaac Mainwaring.