Back on topic........well almost.....I don't think I sound posh but was once accused of it. My accent still has traces of Suffolk where I was brought up, tho some people think I come from Devon, same as my husband! Oh, and lost count of the number of people who've said I sound like Pam Ayres!
But with a Scottish mother and 30 years of living in Scotland I do try to sing in Scots: would never think of trying to "translate" or anglicise a song like "Yellow on the Broom" for example. Ye think ye're daein' nae sae bad, then aebody says "why canna ye sing in yer ain accent?" Whit?