She is a good writer. I don't think I've read anything from before then that I remember (so if I did it was probably at the time it was published or close to).

I've read several of Jean Plaidy's - I've enjoyed her Tudor based novels particularly but I've liked almost all of the ones I have read - I didn't care for her book about George III, but it may have been part of a trilogy, I felt it ended at a rather strange point and most of her books seem to have natural ending points.