Emmylou Harris, Apollo Hammersmith, London

More than 30 years into her career, Emmylou Harris could easily be resting on her reputation. Once the protégée of the late, great Gram Parsons, she's gone on to sing with an assortment of legends, among them Neil Young, Willie Nelson, Bob Dylan and Johnny Cash. Now, of course, she's an institution in her own right, as well as the principal exponent of a genre which fills in the gaps between folk, rock and country. Since 1995's pivotal Wrecking Ball album, on which she teamed up with the U2 producer Daniel Lanois and began writing her own songs, she's enjoyed a creative surge which other artists would gladly tear off limbs to attain.

Elegantly clad in a tight-fitting black dress, high-heeled boots and with cheekbones you could hang your coat on, Harris is a calmly refined presence. Tonight she talks only briefly between songs, evidently preferring to get on with the business in hand. Accompanied by Spyboy, a superb backing trio which includes the guitarist Buddy Miller, the first half of the show is built around this year's ravishing Stumble Into Grace album. They're songs with heavy duty themes - love, regret, death - though sung with an urgency and authority that staves off sentimentality. "Strong Hand'' is a moving tribute to the late June Carter Cash (wife of the late Johnny Cash) while "Time in Babylon'', a cautionary tale of American amorality is "respectfully'' dedicated to George Bush. "Can You Hear Me Now?'' ("God, was I in a dark mood when I wrote that one!'') is a heartbreaking ode to loneliness.

Despite the rich seam of melancholy, Harris, as ever, brings a spiritual, life affirming quality to the songs. Her voice is an exquisite instrument, crystalline at the core though pleasingly ragged around the edges. When she reaches for the high notes her voice takes on a sweet girlish quality that belies her years.

In the second half of the set we travel further back into her career. The 1975 classic "Boulder to Birmingham'' ("I would walk, Lord, all the way from Boulder to Birmingham if I thought I could see your face''), "Hickory Wind'' and "Together Again'' (dedicated here to Phil Kaufman, the madcap character who took it upon himself to cremate Gram Parsons' body in the California desert) underline Harris's kinship with old-style country though "Born to Run'' joyously brings her honky tonk leanings to the surface.

Clocking in at just over two hours, tonight's show might normally test the endurance of even the most ardent fan. In reality it's a stunning set and by the encore the clearly smitten crowd are begging Emmylou for more. She is a legend, after all.