G'day,
I have a video tape of Don Bradman, a much more revered person in Oz than mere royalty could ever be, (one of our greatest sportsmen and the world's best ever batsman – cricket you know) and his accent and inflections changed markedly from the 1930s & 1940s to the 1990s.

How can we hold up the Queen's English as correct when she pronounces Australia as Orstralia (or Awstralia if you always treat 'r' as a consonant)?????

And the following, taken from my 1971 dictionary is relevant here:-

.... we must recognize one very important characteristic of the human speech mechanism which actively works to prevent our pronunciation from ever achieving a state of complete uniformity. Human beings are not talking machines; our control over our speech organs has not and cannot have machine-like precision. Consequently we do not always succeed in pronouncing a word in exactly the same way on all occasions. At any one moment the variation in sound may be quite small and of a transient nature, passing unnoticed. Over long periods of time, however, and with large numbers of individual speakers involved, this variation may develop into an appreciable, rather more longstanding pronunciational change. Such a change may he discernible in the speech of all speakers of the language in question. It may equally be limited to the speech of certain groups of speakers, while the speech of other groups exhibits a different pronunciational change or no change at all.

Cheers,
Alan

(In Oz where we speak the most perfect English of all.)