Murder Is Easy question

I figured out the killer rather late in the book. I began to suspect it when Miss Waynflete was so excited to hear of the case, and like she was happy that Mr. Esterfield was the suspect. I really caught on when she caught on when she insisted that she and Bridget have tea. Then on their walk to deliver the clothes she kept asking Bridget if she was sleepy, and I just knew then that she was the killer. I was wrong on the motive for the murders though, all the way till when Miss Waynflete explained why she killed. I was way out in left field on the motives. When did y'all get it?