Kay was quite well born, according to Mary Aldin. But her father who was a gambler had to resign from all of his clubs, after some card bussiness. He had died shortly after. Her mother had moved the French Riviera and had lived a scandalous life there, bringing Kay up at various hotels.
She thought that she stood to inherit 50000 pounds after Sir Matthew Tressilian upon Camilla Tressilian's death. The misunderstanding happened because she had heard that the inheritance would be divided between 'Neville and his wife', which she took to be Neville and his legale wife. But Sir Matthew's will clearly stated that the money was to be divided between Neville and Audrey Strange. Neville and Audrey's divorce couldn't change that.