The term dialect, used in regional variation, should not be confused with the term accent. Standard English, for example, is spoken in a variety of accents with regional and social associations: Liverpool, Boston, New York, etc. Yet, people live in such places show a uniformity to one another in grammar and vocabulary because they speak Standard English and the differences is in how they pronounce words.
Received Pronunciation (or RP) is the eminent English accent. It was established as prestigious in the late nineteenth century. It is usually associated with a higher social or educational background, the BBC, the professions, and teaching English as a foreign language. Those who use it are regarded as speaking 'unaccented' English because it lacks a regional association within England. Other names for this accent are the Queen's English, Oxford English, and BBC English. Yet, it is not necessary to speak RP to speak Standard English because Standard English can be spoken with any regional accent.
There is a general leveling of accents within the British Isles. The changes are well documented; there is a variety of factors involved in the changes that occur in cities. Estuary English is a development of RP reflecting a power shift in London towards the world of finance from that of inherited position and traditional bureaucracies. A feature of it is the use of glottal stop fir /t/.
The generalized accent in North America is General American or network English. It is associated with announcers on the major television networks. Other languages do not have equivalent to RP; German is spoken in a variety of accents, none of which is seen better than any other. Educated regional varieties are preferred rather than an upper-class accent that has no relationship to personal achievement. However, it is impossible to speak English without an accent. There is nothing called an 'unaccented English.’ RP is an accent, social and not regional. Different accents have different evaluations arising from social factors not linguistic ones.