Dr Coles

In the short story A Christmas Tragedy, Dr Coles is a physician employed at the Keston Spa Hydro. While a guest at the hydro, Miss Marple consulted him about her rheumatism. He told Miss Marple that Jack Sanders had asked him to look in on his wife Gladys. She had been "seedy" of late, perhaps with a bad case of indigesgtion.

This news struck Miss Marple as suspicious because Gladys had told her that very day that she had a wonderful digestion.