There are little features that mark out posh speech from just standard RP. These things are probably very difficult for learners of English to notice but an English native speaker would pick up on them almost immediately. To a large extent it's clear English with every sound it clearly enunciated. So I need to do more episodes that cover these types of speech in more depth. The best way for you to notice these things is to listen to a lot of samples of people speaking in these ways.