I'm firmly with Mike (theGM one) on this.

When one sings a song that comes from a part of the English-speaking world different from one's own, there are pros and cons to assuming the corresponding accent -- whether deliberately or by unconscious imitation of one's source.

I loved it when I heard Maggie Holland sing blues in an English accent. It can work and it certainly did with her. But it might not with other singers or for other listeners.

Personally I make a distinction between Scots and the rest, partly because Scots has some claim to be a language rather than a dialect (but let's not get side-tracked into arguing about that) but mainly because, as Taconicus mentioned, English pronunciations of Scots words don't sound right; and because many rhymes don't work.

When I hear a Scots song sung in an English accent with just an occasional Scots word such as "frae" instead of "from" and "hae" instead of "have", to me it just sounds wrong.

I will either sing in Scots (generic, based partly on "staying" near Edinburgh for part of my university career but mainly on listening to lots of Scots singers from all over the country) or, if I can manage it, anglicise.

Anyway it is utterly daft for a British singer-songwriter singing their own song to use anything other than the same accent that they speak with. It may sometimes be necessary to adapt both for a particular audience, but if the audience can understand the introduction they can understand the song.

Richard