 After Wilmot's death, his niece, Olivia Serres, claimed that he was the pseudonymous author of the famous Letters of Junius and an influential friend of major writers and politicians.She later also claimed that he had been secretly married to a Polish princess, fathering a daughter by her who had married into the British royal family.Serres asserted that she was the child of this marriage and therefore deserved the title "Princess Olivia".