Complex sentence: In 1989, he employed the Gothic style to create a mansion in London's Regent's Park, ironically the plan was based on Palladio's Villa Saraceno, which it was felt would convert to the Gothic style.
Split into simpler sentences: In 1989, he employed the Gothic style to create a mansion in London's Regent's Park. Ironically, the plan was based on Palladio's Villa Saraceno, which it was felt would convert to the Gothic style.