In the short story Christmas Adventure, Gladys was a kitchen maid at the house of Squire Endicott and his sister Miss Emily Endicott. She broke the chinaware mould holding the Christmas pudding intended to be served for Christmas dinner. The cook was thus obliged to serve up a pudding which had been intended to be served later.
This is the first of Christie's characters named Gladys. The name would go on to become one of her favourites for domestic staff. In subsequent works, there would be some 23 characters by this name (and counting), most of whom were maids or secretaries.