Glasgow's Big Big Country festival may have missed out on the opportunity of promoting rare Scottish appearances by former Byrds in consecutive years, with the cancellation - due to illness - of its Chris Hillman concert tomorrow. but its delving deeper into Americana continues apace, with the festival opening and closing with two artists for whose outputs that term might have been coined.

Appearing at Glasgow Royal Concert Hall on June 30, by way almost of a postscript to the main programme, Taj Mahal has followed up his early penchant for ''old folks on the back porch'' delta blues by moving upriver to soul and rhythm and blues, and on to explorations of Caribbean and Hawaiian music.

Whereas Taj Mahal has surrounded himself with slick musicians, however, opening attraction Leo Kottke has spent the past 30 years travelling alone, his distillation of blues, bluegrass, country, you-name-it finger-picking on six and 12-string guitars causing guitarists everywhere to contemplate giving up or practising damn hard.

Friends including Chet Atkins and David Z, sometime collaborator with the artist formerly known as Prince, have helped Kottke out on record, but in concerts, which take up 80% of his year, he stoically follows the Garbo principle.

''I'm too cheap to take anyone else on the road with me,'' he laughs in the foggy voice familiar from recordings onwards from 1971's Mudlark, which marked his singing debut following its heart-breakingly accomplished instrumental predecessor Six and Twelve String Guitar. Kottke's first instrument was the trombone. But at the age of 12, all the illnesses that can come a child's way hit him.

''For about two months I was so bad I was literally on my back, couldn't do anything, certainly couldn't play the trombone,'' he recalls.

His mother bought him a toy guitar on which he taught himself an E chord. ''I can still hear it - that guitar sounded like cats fighting in a bag - but that one chord got me out of bed. After that, I was hooked.''

Kottke's experiences subsequently are less a tale of music as the healing force than of making music in adversity. A spell in the US Navy left him with a permanent hearing impairment.

More recently, he suffered from tendonitis in his right arm which meant that he could play for only five or 10 minutes before his hand froze. ''I had to stand there and pretend that everything was OK when all the time I was playing really clumsy stuff, with no technique. It was horrible.''

At one point he thought he'd have to give up. Instead, he completely relearned how to play. He stopped using thumb and finger-picks, which curiously enough he'd been warned might cause him harm some years before, and says now he is 100% better as a musician than he was before - which news will be no soft blow to those who have tried to emulate him. ''In the long run, having that problem's been a boon,'' he says. ''But it's an awkward way to improve your guitar-playing.''

n Leo Kottke plays the Old Fruitmarket, Glasgow, tonight. Other Big Big Country concerts feature blues singer/guitarist Chris Smither (Friday); singer-songwriter Loudon Wainwright lll (Saturday); gospel choir the Blind Boys of Alabama (Sunday); actor turned singer Elaine C Smith (Thursday, June 4, and Friday, June 5); blues singer/guitarist Eric Bibb (Friday, June 5); and

singer-songwriter Rab Noakes and former John Mayall's Bluesbreaker, guitarist Walter Trout (Saturday, June 6).