A long Wikipedia article on West Country dialects (“any of several English dialects or accents used by much of the indigenous population of … Cornwall, Devon, Somerset, Dorset, Bristol, Gloucestershire, and Wiltshire”) has some very interesting tidbits, like this:
In the Bristol area, a terminal “a” (realised as [aw], c.f. Albert as “Awbert”, cinema as “cinemaw”) is often perceived to be followed by an intrusive “l”. Hence the old joke about the three Bristolian sisters Evil, Idle and Normal — i.e., Eva, Ida, and Norma. Also the name “Bristol” itself (originally Bridgestowe, variously spelt).
The West Country accent is probably most identified in American English as “pirate speech” — cartoon-like “Ooh arr, me ‘earties! Sploice the mainbrace!” talk is very similar. This may be a result of the strong seafaring and fisherman tradition of the West Country, both legal and outlaw. Edward Teach (Blackbeard) was a native of Bristol, and privateer and English hero Sir Francis Drake hailed from Tavistock in Devon. Gilbert and Sullivan’s operetta The Pirates of Penzance may also have added to the association. It has also been suggested that Westcountryman Robert Newton’s performance 1950 Disney film Treasure Island may have influenced people’s preconceptions of what accent a pirate “should” have.
Unfortunately, as the Masters of Wiki say in a box at the top of the page, “This does not cite its references or sources,” and I imagine it is not devoid of misstatements; if anybody has corrections to make, please do so (and you can, of course, edit the Wikipedia article yourself).
Thanks for the link, Betsy!