In the first part of this discussion and explanation on the concept of Standard English, Tim Bowen focuses on British English.
On closer examination, however, this standard appears to be notoriously difficult to define. It is to some extent social, with some of its sounds closely identifiable with the traditional pronunciation of the privately educated aristocracy and upper classes. On the other hand, members of this exclusive group appear to use fewer phonemes than the 44 of standard RP. Their pronunciation of the words "tar", "tyre" and "tower" would probably be identical, namely /ta:/, whereas for most speakers of British English these three words would be pronounced in three clearly different ways. Similarly, the word "house" is often pronounced as if it rhymes with "mice" rather than "mouse", this one being a particular idiosyncrasy of the above-mentioned group.
So, if "Standard English" is not the English of the numerically insignificant British aristocracy perhaps it is regional? If we take Oxford as an example, there are doubtless numerous people working and studying at the university there whose English approximates very closely either to RP or to the reduced version of RP spoken by the English upper classes, but such people are certainly a minority in the city of Oxford as a whole. The local accent is very different from RP and, as such, the term, "Oxford English" is extremely misleading.
If we can attribute RP to a specific area, then it is probably to the South-East of England, but it is in no way representative of the vast majority of the people who live in this region, most of whom are beginning to speak a reduced form of London English widely known as "Estuary" (from the Thames Estuary, bordered by Essex and Kent, where this accent predominates). The spread of this particular "Standard English" appears to be driven by two factors: migration from the London area into rural areas of the South-East and the widespread popularity of television soap operas set in London. As yet, Estuary has not made any inroads into the traditional dialects of the North of England, the English Midlands and the South-West, let alone Wales and Scotland, but its influence in the South is proving remorseless, with the traditional rural Sussex accent, for example, becoming completely swamped. At this point, it is arguably the most widely used dialect in the country and has, therefore, the greatest claim to be regarded as "Standard English".
There is, however, another important factor in this equation, namely the influence of American English. With far fewer regional accents and dialects than British English, American English can be regarded as being much closer to having its own standard form. There is already a large and growing bank of American vocabulary in British English (witness the increasing use of verbalized nouns), and cultural influences, mainly through television, from the world’s most powerful economy may soon have a noticeable impact on British English pronunciation.
While British accents are traditionally regarded as "quaint" in the United States, the opposite is most certainly not the case and there is already a "mid-Atlantic" accent observable both amongst Britons who have spent periods of time in the USA and amongst certain professions with close links with US culture, notably the music profession. So far, "mid-Atlantic" has only a limited presence, but it may only be a matter of time before the battle lines are drawn between Estuary and mid-Atlantic for the struggle to become the "Standard English" of the United Kingdom.