British Accents are varied and plentiful. Every region has its own accent and some are more accepted than others. You can find many videos on YouTube showcasing the variety of accents available. Some Brits like to change their regional accent to a more accepted RP accent. This is also called the BBC broadcasting accent even though they are now using a more varied palette of accents for their announcers.
Hollywood also shows a certain predilection for the RP accent and you will find most villains in movies are English nowadays. This preference is so well known that famous car manufacturer Jaguar has made an entire campaign around this fact (see video). Comedy program the Last Leg also discussed this phenomenon with David Tennant and discussed multiple accents and their possibilities in Hollywood. (from 0:53)
Another thing about British accents is that most of them are seen as uneducated, this is because most highly educated people adopt the RP accent or a milder regional accent. Strong regional accents are often seen as uncultured. The first QI video shows how people think about fighter pilots in the war and how they sounded. They all believed that the pilots were posh because the actors playing them were. They also discuss a survey of the preferred accent of pilots nowadays.
The last video of Stephen Fry being fooled by a Geordie accent is ended by the line “they must go to school, it is just ridiculous” this shows a wider belief that strong accents are seen as uneducated.
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