Steve Earle and the Dukes (and Duchesses), Royal Festival Hall, London

"To those of you who thought there was a support act, you've missed half the show," quips Steve Earle to latecomers at the Royal Festival Hall. Steve Earle and the Dukes (and Duchesses) have already been playing for an hour, with two more yet to come. As he chuckles through his beard, you get the sense that "slowing down" isn't a phrase which has entered Earle's vocabulary: a seasoned country star, he retains the rambunctious enthusiasm of a teenager.

Earle's band instantly display an unconscious chemistry, the singer given free rein to vent during the anti-BP protest song "Gulf of Mexico" and to emote in "Every Part of Me", a paean to his singer-songwriter wife, Allison Moorer, herself a member of the Dukes. These early forays set the template for what is to come, bouncing off an insistent country backbeat provided by Will Rigby's exemplary drumming.

Stylistically, the gig swings from intimate to intense and back again, but the Texan singer's honest vocals bind these disparate threads together. Every track, from the maudlin shanty "Molly-O" to the haunting nostalgia of "The Mountain", is sincere, and despite occasionally lurching towards preachiness, the colossal 33-song set largely stays on course.

What's also evident throughout is the admiration Earle has for his bandmates, as Moorer, bassist Kelly Looney and husband-and-wife duo The Mastersons all get a turn at the mic, with mixed results. Strangely, all impress more when playing Earle's songs than their own, Chris Masterson's aching, melodic guitar riffs arcing beautifully over the entire set.

In among the thrills of "Copperhead Road" and "City of Immigrants" are a few lulls, however. Where tonight's show excels is in the extremes of the sound spectrum, either lilting with tender lyricism or soaring with a bombastic country swagger. A little too often it uncomfortably treads the middle ground, a few songs simply washing over the crowd, and Earle's beguiling brand of personal, forceful country music becomes frustratingly diluted.

Yet at its best, this show is superb. The first of tonight's two encores is its pinnacle, incorporating the chilling "Billy Austin", the raging "The Devil's Right Hand" and fan favourite "Johnny Come Lately". The first, a thought-provoking tale of death-row woe, is lit up by Earle's regretful, pained vocals, while the latter pair hum with a foot-stomping intensity it's hard to resist. Three hours after it began, the show closes, and even latecomers have got their money's worth.