too bad
It's difficult to know how to apportion things between Davis, Cromwell and the writers, but one way and another the Mildred character, though very memorable, isn't in context very plausible, and not just because of the weird accent. How much better the film would have been if Mildred, though overall a nasty bit of work for sure, had possessed qualities that made her somewhat attractive to us, and so more understandably attractive to Philip, even if this came and went*. Her complete (and dare one say cartoonish) revoltingness makes the whole story that much harder to swallow, and it needn't have been that way.
*Just one example: Marie Windsor/Sherry in The Killing.
"I beseech ye in the bowels of Christ, think that ye may be mistaken."