Van Morrison, Shepherds Bush Empire, London

It seems unlikely now but Van Morrison, the barrel-chested little man wearing dark glasses, his Homburg clamped down tight, was once one of our most fearless musical adventurers.

Astral Weeks blended literary allusion and Belfast childhood reminiscences with blues, jazz and soul, and it provided a gateway to future explorations. By the Eighties Morrison was a returned exile, the incantations and invocations of "Summertime In England", regularly reworked to mesmerising effect onstage.

In recent years, however, he appears to have lost the ardour of old, drawing back into a sometimes amiable but essentially unchallenging comfort zone. While the new album, Magic Time, is a partial return to form, the set-opener "Keep Mediocrity At Bay" is a medium-paced thumper whose title sets the tone for the bulk of what follows. "Stranded", with the wandering pilgrim exile "stranded at the end of the world", provides a rare glimmer of transcendence and self-awareness. Thereafter he ignores the album's key track "Celtic New Year" in favour of a set that pivots around the jumpin' jive club-jazz favoured by his underwhelming 2003 release What's Wrong With This Picture? And, of course, there is no "Summertime In England".

"Moondance" is padded out to become an elongated supper-club showcase for the band, and encore standards "Brown Eyed Girl" and "Gloria" are dispatched with little love or involvement. The one attempt to break into the heart of a song, with the a cappella interlude in "Precious Time", is quickly abandoned, leaving the impression of a performance that merely took care of business while an eye was kept on the clock.

There may be reasons why Morrison has retreated into the musical equivalent of a gated community. Johnny Rogan's controversial biography No Surrender, which somewhat fancifully attempts to draw a link between Morrison and his fellow countryman Ian Paisley, probably hasn't played well with him. But artistic fatigue and an embittered world-view, revealed in "They Sold Me Out", may have as much to do with it.

There's a story that a middle-aged Belfast couple told him that his set was much shorter than the Bruce Springsteen show they had recently seen. "Never mind Springsteen," came the reply, "I'm trying to get it down to five minutes." There was not even a window that short where he flew free and left the listener catching his breath.