Artist with fizz

'When you're using an image such as a Coca-Cola logo, you're always slightly concerned that someone's going to take you to court,' says the artist about to start on a 6m-high installation on the South Bank. No, it isn't Banksy. This art rebel might brush with the law but he also happens to be both a pensioner and a knight of the realm.

And, despite his past subverting images from advertising as one of the best-known British pop artists, Sir Peter Blake is now seeing The Coke Side Of Life in a new commission for the fizzy drink brand. 'It was slightly strange to be commissioned by them,' says the 75-year-old creator of the iconic Beatles Sgt Pepper album cover. 'But with a job like this, if I couldn't do what I wanted, I wouldn't do it.'

Accusations of selling out might be applicable if this wasn't someone whose work was based on the friction between art and commerce. 'Of course, the two can co-exist,' he says. 'Most artists are professional - it's what we do as a living.'

Blake's relationship with brands has not been unquestioning, either: in his 1961 Self-Portrait With Badges, he opted for a badge promoting Pepsi, the second most popular soft drink, as one of his 'American trophies'. And he has co-opted Coke logos into his artwork before, often for reasons of aesthetics. 'I used Coke out of a sense of admiration for the graphics; the word in a fairground script is a wonderful image,' says Blake. 'I wasn't saying Coke is a great drink, just a great graphic.'

The installation should offer more than a billboard. A 6m by 3m canvas, it will show his signature crowd-of-people-ascutouts emerging from the neck of a Coke bottle. Blake will be constructing it on the spot throughout next week.

As a piece of public art, it is a continuation of pop art's search for accessibility. 'I'm still making a form of pop art,' he says. 'The original concept was to make the art equivalent of pop music, it was meant to be populist.' But he now picks up snippets from his DJ daughter. 'I'm more interested in pop culture as a scholar than a participator,' he decides. He has also produced a series of works featuring Marcel Duchamp travelling around the world on a rock'n'roll tour bus meeting the Spice Girls, Elvis and Tracey Emin. He has, however, worked out which brands can be messed with and which can't. 'I tend not to use Disney because I know they chase things up...'

From tomorrow until Aug 31 (under construction until Aug 23), Jubilee Gardens, Jubilee Walk, South Bank SE1. Tube: Waterloo