I had to laugh at the Gift to Music CD labelled Celtic - it has several very-rooted-in-English-music musicians performing a selection of non-English songs and tunes ( the recording company obviously couldn't find anyone to get their tongue round the various Celtic languages, so the Welsh & Gallic songs are rendered as airs only.)
I am sure that these artists give an excellent rendition of everything they turn their hand to - Paul Sartin, Benji Kirkpatrick, Jon Boden and Ian Giles would be hard to fault at the best of times. But, why not get them to perform what they do best - English music and song!