 In 1950, Heyer began working on what she called "the magnum opus of my latter years", a medieval trilogy intended to cover the House of Lancaster during that period.She estimated that she would need five years to complete this project.Her impatient readers continually clamoured for new books, however; to satisfy them and her tax liabilities, Heyer interrupted herself to write Regency romances, such as "April Lady" (1957) and "Charity Girl" (1970).