Blondie, Westonbirt Arboretum, Gloucestershire<br/>Kele, Digital, Brighton

The strange and beautiful career of Debbie Harry is now entering a fascinating phase. At the age of 64, when most rock chicks have long since retired, it's clear that this pop icon has no intention of stopping.

That figure may come as a shock to some, especially since most of Harry's post-punk peers are now around the 50 mark, but the defining sex symbol of the late Seventies was always older than she let on.

There are all sorts of surprising stats one can bring up here: born in 1945, Harry is two years the senior of Mary Weiss of The Shangri-Las, whose girl group sassiness she drew on heavily in Blondie's early years. And she's also two years older than Marc Bolan, who had already gone superstellar, faded away and died by the time Blondie had their turn. The opening couplet of "Dreaming" – "When I met you at the restaurant/You could tell I was no debutante" – was, therefore, deadly accurate. With her worldly-wise attitude and calculating eyes (they added you up and found you wanting), Debbie Harry was always the anti-ingenue.

And, after one big comeback and a succession of aftershocks, she evidently intends to continue performing, like Marlene Dietrich, well into her twilight years, or perhaps even, like Josephine Baker, till the day she drops. The vital difference is that Blondie in the 21st century is no cabaret nostalgia act. Or at least, not entirely.

To the bemusement of an audience here for the hits, this tour is largely a preview of Blondie's upcoming ninth studio album, Panic Of Girls. In some ways, I empathise with the picnickers. This may feel more like a Ukip conference or Countryside Alliance rally than a pop concert, and the crowd may be mainly comprised of Barbour-jerkined Ellen MacArthur types and their ruddy-cheeked offspring, but they've paid their money and they're disappointed to go home without hearing "Denis" and "Sunday Girl" (for me, the absence of "Union City Blue" is the real killer), especially when room is made for an irrelevant cover of Taio Cruz's "Break Your Heart". I'm reminded of Homer Simpson heckling Bachman Turner Overdrive: "No! No new crap! Play "You Ain't Seen Nothing Yet"!"

But this setting – an arboretum (it's like a zoo, but for trees) in the middle of the Cotswolds – isn't Blondie's ideal setting in any case. Seeing Clem Burke wearing a CBGBs T-shirt behind his big Perspex drum shield is poignant: if ever there was a band who need to do what The Stooges have done, bring it back indoors to the theatres and give it some punk rock, it's Blondie (and this coming Wednesday's gig at the indigO2 in London is probably as close as we'll get).

Harry looks, it must be said, incredible. After appearing a little grandmotherly in recent years, she's recognisably Debbie Harry again: plutonium blonde hair, Grace Kelly shades, military jacket, punky pleated skirt, and – of course – the greatest cheekbones Mother Nature ever carved. And, as though looking that way gives her licence to let go, she's got a new lease of life, doing that daft rigid-armed, side-to-side dance from every video you ever remember. Her voice struggles with some of the high notes on "Maria", but on the less demanding "Picture This", "Presence Dear" and "Tide is High", she's in complete command.

The new stuff, while not a straight carbon copy of the classic material, is a Warholian screen-print variation on it, as indeed is their bar-code logo, a nod to the Parallel Lines sleeve. This figures: Blondie are Pop Art in musical form, Warhol's worldview rendered (in the) flesh.

And the hits, when they come, are no robotic regurgitations either. "Call Me" is rendered as, essentially, a live mash-up with Muse's "Uprising". On the insane and inspired hip-hop homage "Rapture" she freestyles about petrol pumps and China, and breaks off in the middle of "One Way or Another" to ad lib "I guarantee a certain amount of results if you adopt this philosophy. Flexibility in our lives and our bodies ...."

Some songs, however, are left intact. "Atomic", for example, with its wild-west heroic riff and Moroder beats, and the peerlessly disdainful disco of "Heart of Glass". You don't mess with perfection.

Watching Kele Okereke launch his solo career lends a whole new meaning to the term "vested interest". Because the black-vested Bloc Party singer looks more interested in performing his electro-centric debut The Boxer than in the stand-offish indie stylings of Bloc Party.

Wading into the crowd, literally getting into the mix (rather than farming it out to Armand Van Helden), he is, as lyrics like "I am turning into the man I used to be" suggest, taking control and reclaiming his identity.

He's even writing his own reviews: glancing down at a pendant made of red, amber and green LEDs, he says "I seem to have a flashing light in place of my heart. How symbolic ...."

Okereke's demeanour is more like that of the MC at a Rio carnival after-party than a guy doing a gig under the arches on Brighton beach, and the atmosphere is more like a rave than a Thursday night gig with a 10pm curfew: sweat, green lasers, hands in the air, and so much smoke that passers-by on the promenade pause with concern.

"Ooh, what's this?" he says coyly, putting a guitar around his neck. "I haven't seen one of these in a long time ...." He bats back requests for Bloc Party numbers for a while ("'Helicopter'? What's that?"), but it isn't long before he relents, with BP's rapturous "One More Chance" and a Hi-NRG encore of "Flux", proving that sometimes pleasing the crowd and pleasing yourself can be one and the same.

Next Week:

Simon Price encounters two very different legends: the Reverend Al Green, and the somewhat less holy Ozzy Osbourne