Old Mother Riley's New Venture

The owner of a five star London hotel leaves for a holiday, and to everyone's surprise promotes Old Mother Riley from kitchen dishwasher to manageress. Chaos ensues, and Mother Riley and Kitty are suddenly suspects in the theft of the Royal Hula Diamond. Somehow along the way, also manage a trip to a beauty parlour, a banquet with Arab royalty, some Saint Patrick's Day celebrations, and a climactic custard pie fight.