Van Der Graaf Generator @ Barbican, London

While Van Der Graaf Generator are 1970s prog rock survivors, they’re not a band to rest on past laurels. Their 2005 reunion, following a 27-year hiatus, has so far resulted in three albums: Present, 2008’s Trisector and, more recently, A GroundingIin Numbers. Their current tour leans heavily on the new material while not rejecting the old.

London’s Barbican is the ideal venue for them. On the one hand a ’70s monstrosity of concrete and brick, deliberately designed without an obvious grand entrance in order to be egalitarian and modern, it’s difficult to navigate and easy to get lost in. On the other, it has a stark elegance and beauty that’s both tied to its time and – just – transcends it, nodding to both the past and the future at once. Like the band’s second reformed album Trisector, a harsh post-rock evolution of industrial phasing and percussion, there are no soft angles here.

The evening is divided into three parts. The first begins with the duelling, phasing keyboards of Trisector’s Interference Patters, which draws together both parts of the band’s history: prog vocals over more challenging percussion and keys. Yes, it sounds like an A-level classical music project gone wrong, but that’s what progressive rock should sound like, surely. This leads into Mr Sands, from the new album though more ’70s-sounding than Trisector’s fare, and the dreamier, low stoner comedown of Your Time Starts Now. The trio end the first act on a mash-up of new track Mathematics and Nutter Alert, from 2005 comeback album Present.

For the second act, Peter Hammill picks up a guitar to replace one of the keyboards, pleasing a crowd who are nearly universally the far side of 50 with Lemmings, one of the few pre-reformation tracks on offer tonight, before it’s back to the newer material, albeit the less challenging and more jazz/blues fare of Trisector’s Lifetime and A Grounding In Numbers’ Bunsho. This may be as commercial as they come but it still shows the punk edge that saved them from the worst of the mid-70s excesses.

Returning to the dual keyboard configuration, Hammill and Hugh Banton phase their way through All Over The Place before Over The Hill’s minimal start builds on the bare bones to something all together more explosive, displaying a knowing self-awareness as they leave behind the new material to delve back into the past with 1975’s Scorched Earth, its dark fairground organs sounding ironically modern in its hints of a thousand Yorkshire post-rock children, before ending on the epic and spectacular Childlike from 1976’s Still Life.

Prog should be all psychedelic flares and big hair: Van Der Graaf are darker than this, tilting towards the genre’s harder comedowns even from within its midst. Tonight, they’ve shown not only how new, modern and genuinely progressive their songwriting is, but also how they’ve had no reason to abandon the past in order to develop it. A Grounding In Numbers is, ironically, less forward sounding than its predecessor, but perhaps that’s deliberate. Difficult second (comeback) album out of the way, they’re happy to relax into a sound with which they’re entirely comfortable. In the dark belly of 1970s modernist architecture, they’ve found their spiritual home.