In the novella The Mystery of the Spanish Chest, Linda Spence is the wife of Jeremy Spence. They live in a minute house in Chelsea. She and Poirot had a fairly long interview. She was in fact delighted to meet Poirot as she wanted to hear all the latest news. She was of the opinion that Margharita Clayton and Major Rich were certainly having an affair. As for the telegram which called Arnold Clayton away being a fake, she was not surprised. Just the kind of hoax to play to get the husband away so that the wife and her lover could spend the night together.
According to Linda Spence, Margharita Clayton had an extraordinary effect on men. She had something in her which made men mad about her. She likened it to the situation in Othello. This proved to be an important thought and Poirot would later credit her with setting him on the right track about who had committed the murder and why.
The Spences are not featured in film adaptation of the story in Series 3 of ITV's Agatha Christie's Poirot.