It’s hard to fathom why Van Morrison, never looking back except to mull over real and imagined ancient slights, has decided to re-visit Astral Weeks, arguably his best-loved album. But, 41 years on, he’s decided to play it in its entirety. Perhaps given the mean-spiritedness of his recent output, he feels the need to embrace more innocent, more optimistic times.

Hiding behind sunglasses and underneath a hat (although some curiously orange hair protruded at neck level) and wearing a dark leather suit which cast him as a giant overcooked chipolata, the 63-year-old gave almost nothing away during last night’s second of two Albert Hall shows — Eric Clapton attended on Saturday, Yusuf Islam yesterday — deigning only to speak when introducing Astral Weeks’s centrepiece Madame George, cheerily explaining that the song was set close to South Kensington and that its protagonist had smoked opium.

More chat and more explanation would have been welcome — he might well be worth listening to — but the music itself was timeless in 1968 and in 2009 this engrossing, singular, often magical song cycle remains more than capable of luxuriating in the embrace of an 11-strong, tightly rehearsed band including guitarist Jay Berliner who played on the original.

And while Morrison may be looking back, he was not standing still, tinkering with the running order, turning the sprawling Ballerina into near-gospel and Sweet Thing into a rollercoaster where Morrison’s acoustic guitar battled with Richie Buckley’s flute and both emerged victorious.

Cleverly, Astral Weeks was only the second half of the tale. Before the interval, his band numbered 15 and Morrison grappled with some old favourites, not inevitably to be confused with old hits.

Testing his clearly terrified accomplices, Morrison abandoned any set list and barked out song titles as they began, forcing those who were multi-instrumentalists into momentary panic. And once the musicians eased themselves into a song, Morrison conducted them with his hands behind his back, altering volume and tempo as the mood took him, all while facing the audience.

The tension was almost palpable and it made for edge-of-the-seat fare. I swear Morrison chuckled loudly during a startlingly urgent trek through Caravan, which veered from gruff bluster to something transcendentally spiritual, while And The Healing Has Begun and the call and response vocal duet with Buckley on Common One were so emotionally uplifting, you could forgive Morrison almost anything. Even that tuft of orange hair and those leather trousers…