Complex sentence: When Dell died in 1764 he left Flitwick Manor to Anne Fisher, his goddaughter, but as she was only seven years old her father Jeffrey Fisher was the proprietor until she turned twenty-one.
Split into simpler sentences: When Dell died in 1764 he left Flitwick Manor to Anne Fisher, his goddaughter, but as she was only seven years old. Her father Jeffrey Fisher was the proprietor until she turned twenty-one.