Question about Stereotypes?

Why are the English usually stereotyped as smarter/ more sophisticated than the Irish, Scottish and Welsh? In Television Programmes the English are usually portrayed as snobbish and intellectually/socially superior to their neighbours whilst the Irish and the Scots are drunken violent mindless brutes and the Welsh are just plain stupid/partake in bestiality. Why does the media feel the need to categorise the UK like this? stereotypes are nonsensical.