Laces for Milady was originally published in May 1981. This cover is a June 1986 reprint. Joan Smith writes about Priscilla Denver and her rage at finding that her house didn't actually belong to her but to the Duke of Clavering.
Allan Kass illustrates this cover (which is the same as the 1981 version) with our couple standing on the grounds of a large estate. They wear riding dress and it's fun to see the detail with the trees, pond, statue, etc. Our heroine doesn't seem quite happy with the hero and this inquisitive look makes one pick up the book!