Gil Scott-Heron, Somerset House, London

If you don't know Gil Scott-Heron, he's the man behind the classic 1970s track "The Revolution Will Not be Televised". If you do know him, you'll either be shocked to hear he's still alive or you'll be aware that his lyrics on racism, poverty and addiction struck a chord with young black Americans growing up in the 1970s and that the so-called "godfather of rap" has been through some tough times of late.

Beset by drug problems, the urban storyteller's career stalled before hitting rock bottom in 2001 with a jail sentence for a drug offence, before a parole violation led to another spell in the joint in 2007.

But the poet, musician and hip-hop harbinger's career is back on track with the release this year of his first studio album in 16 years, the excellent I'm New Here. Produced by Richard Russell (Radiohead, Vampire Weekend and The xx), who signed him as he languished in jail, it offers harrowing poetry to a backdrop of minimalist electro, bass and jazz.

On stage at London's Somerset House, for once on time and with his now trademark flat cap atop his lean frame, he doesn't seem too eager to launch into his new album. Rather, he treats the expectant crowd to a succession of quick jokes, powerful and poetic monologues and hits from his vast back catalogue.

There's a release and a wave of relief when the music starts with the first bluesy lines of "Blue Collar" – he's renowned for chatting for what can seem like an age before starting on his first track. And as the early evening light reflects off the stone surroundings and a hush descends on the courtyard, it looks like we are about to witness a small part of the rebuilding of one of the 20th century's great musical pioneers.

"I'll Take Care of You", a mournful track, perfect for the Chicago-born singer's grizzled and mesmerising baritone, is his only offering from his new album in a set dominated by conversational breaks between songs and blistering takes on old classics including "Winter in America" and "We Almost Lost Detroit", a warning of the dangers of nuclear power.

And despite those three tough decades the man, who through his poetry and combination of jazz and soul paved the way for rap, and then hip-hop, remains fresh as ever, his deep drawl still familiar. His tracks are kept alive by their frequent sampling by later generations of artists including Tupac Shakur, Kanye West, Mos Def and Dr Dre.

But then he disappears backstage for almost 10 minutes. Meanwhile, the well-heeled and overwhelmingly white crowd stands unfazed enjoying the atmosphere and taking the opportunity to refill their drinks. They've invested a lot of time and hope in this unreliable artist over the years and don't seem to mind the 61-year-old taking a break.

And of course he returns, to rapturous applause, to launch into an extended and emotional "The Bottle" and then again for a short encore. Many artists make comebacks, clawing back from the edge of obscurity. Tonight, Gil Scott-Heron's feels more like a rebirth.