Berry and her sister Agnes had a remarkable association with Horace Walpole. They first met him in the winter of 1788, when he was then more than 70 years old. A letter he wrote in October 1788 related how: “he had just then willingly yielded himself up to their witcheries on meeting them at the house of his friend Lady Herries, wife of the banker in St. James's Street”. Walpole developed a deep fondness for the two girls, lavishing them with endearments and compliments. In his letters, Walpole spoke of both in terms of the strongest affection and endearment, in one instance addressing them as his "twin wives". He wrote books solely for their pleasure and dedicated other writings to them. It was solely for their amusement that he wrote his "Reminiscences of the Courts of George I and II" (1789). He established the sisters at Teddington in 1789, and two years later, in 1791, he prevailed upon them to move into Little Strawberry Hill, a house previously known as Cliveden, the abode of his friend Kitty Clive, the famous actress. They lived there for many years.