Theft of Love — Marina Oliver

Linda's new boyfriend Pete enjoyed looking at stately homes. She was horrified, when they went to The Old Grange, where a big re-enactment weekend was taking place, to find he was planning to steal some of the antiques and expected her to help him.
Furiously angry, she found help from a knight in armour, and together they determined to foil the crooks.
Marina Oliver has published over fifty novels and several non-fiction books. Many of her historical novels, twentieth-century sagas, contemporary romances and crime books are now available as e-books.

Previously published as "Her Stolen Heart" under the pseudonym Bridget Thorn.