William Boyd insisted on speaking grammatical English during this series, because he knew so many children would be watching and wanted to set a good example.
This is one of the foremost reasons why I like older movies, and their stars, much more than the newer stuff. I believe movies, TV, books and everything else in our cultures should be geared toward teaching those younger than us good manners and morals. I'm 75 years old, and a military retiree, so during my lifetime I've heard every profanity ever invented. But I STILL cannot stand the filthy language that is so common in movies, TV and books nowadays. There have been several times I've walked out of modern movies because the dialogue was one "F" word after another.