In a related post:
viewtopic.php?p=657204#p657204 I commented that Maynard Keynes, whose command of English and English idiom was beyond reproach, might now (were he still with us) be blackballed from broadcasting owing to his drawling accent. For a short clip:
https://www.youtube.com/watch?v=0PYSFqCSsGU and note in passing his pronunciation of 'cost' as 'corst' - something almost London dialect; the late Deborah Duchess of Devonshire (née Mitford) also did this.
Rhyd6 rightly criticises of those who assume there is only one ('Max Boyce') Welsh accent. To me, the difference is north vs south, with North Wales English (and Welsh) generally sounding harsh, monotone and with a touch of Liverpudlian (e.g. sounding 't' as 'ts'), whereas the South has an almost west country lilt. Certain digraphs are said differently also: in the north, Eirlys is said aye-rlys (or occasionally eee-rlys) whereas in the south it is eye-rlys.
David Lloyd George, who was born in Manchester to Welsh parents but lived almost all his early life in in a very welsh-speaking part of north-west Wales, never managed to put tonal ebb and flow into his speeches: vide
https://www.youtube.com/watch?v=yXmlcGWdNs8The late (and superb) dialect coach Joan Washington, whose comments on some WW1 recordings of English accents are so illuminating (
viewtopic.php?p=550998#p550998) tended to concentrate on regional accents, but it would have been fascinating to have her illustrate how the 40 or so phonemes in ‘posh’ English changed during the 20th C.