I don't know if this has more to do with politics within the BBC than popularity but of all the regular folk on BBC radio there are two english programmes (Sunday-Tim Walker & Wednesday-Mark Radcliffe) a couple of Irish and Welsh programmes and over a dozen Scottish programmes.

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Here's the BBC page which lists their current Weekly/Monthly/Seasonal radio programmes* (and a few one-offs).

- NB open the link in a browser; don't just click the link or it will try to open your 'Sounds' app and this doesn't provide the same information as the web page -
www.bbc.co.uk/sounds/category/music-folk?sort=title

*One regular programme missing from the page above :
Iain Anderson (country, folk, blues and soul) r2
www.bbc.co.uk/programmes/b0074hkv/episodes/player