This is a dialectic language question.
Responses (2)
Not all Brits say "ideer" in fact I don't think I've ever heard one say that before (in person or on television). It sounds more to me like a slurred speech, so it may be a part of a local dialect like you mentioned, because there's dozens of forms of British accents.
Fun fact, in case you didn't know: The Jamaican accent is actually a form of a British accent.
That is not a British dialect, it is an eastern USA accent called "Ivy League" and most often associated with Boston. You should learn your subject before exposing yourself to public judgment. If you had a valid complaint, the English still would not replay because in their world view there are only two languages: English and foreign. And they have no reason to apologize for speaking English.
English, not British. British is a recent invention. It never existed before.