I agree entirely Doug.

Grishka, I don't think we can be sure that anyone 'assumed "r"s where there were none.' It's perfectly possible that this sound (it's not an 'r' actually, just sound like an 'r') predates spelling, and could for all we know have been a majority pronunciation in England at some time - it's just that it's not reflected in the way scholars decided to represent spoken English using the Alphabet.

Another change seems to be senior politicians deliberately (or it is?) dropping their aitches and glottle-stopping their tees. It may have begun with a ploy to unplum, but if enough people in the Westminster Village do it, it may become the norm. And TV may spread it wide, so that in time it will become 'common' (or rather 'uncommon') to use an 'h' or 't' altogether.

Just a thought

Tom