Her employer's request, were it based on the fact that the cross is a religious symbol, would be discrimination but the ban is on the basis that jewelry poses a health and safety risk - and all jewelry is banned, not just crosses! It seems quite clear that, while Mrs. Chaplin may well be disappointed, she is not facing persecution. Mrs. Chaplin claims that she is being asked to "choose between her job and her faith" but this is patently not true! There is no stipulation that Christians must wear a visible cruxific. Mrs. Chaplin can tuck her cross under her uniform while at work without betraying her faith in any way whatsoever.
Whether some of our health and safety restrictions are just a little bit daft is another matter!