Terry Grimley meets two pioneers of 1960s psychedelic art.

It's been a sobering thought for some of us that the less-than-sparkling summer we have just endured marked the 40th anniversary of the so-called Summer of Love.

For those of a certain age, William Wordsworth's famous comment on the French Revolution - "Bliss it was in that dawn to be alive/But to be young, was very heaven" - will always evoke those few months in 1967 when it seemed that youth was taking over the world.

It wasn't, obviously, and there has been no shortage since then of cynics to pour ridicule on the naivety of "Flower Power", but that doesn't dispel the butterfly magic of those brief few months which followed the release of the Beatles' Sgt Pepper album.

Its fragility can be seen with hindsight by the fact that within six years, the Heath Government had introduced the three-day week against a background of industrial unrest and power-cuts.

The 1970s proved to be a troubled and unnerving decade with a style-sense that seemed intent on parodying the 1960s, but if anything, such reflections make the summer of 67 more, rather than less, poignant and fascinating.

Last year, Tate Liverpool revisited it with the first retrospective look at psychedelic art, and now Birmingham's St Paul's Gallery has a show focusing on two artists who helped shape the look of 1967.

Karl Ferris is the photographer whose freaked-out photographs of musicians like the Jimi Hendrix Experience and Donovan helped define the era, while Simon Posthuma was half of the Dutch design team known as The Fool (with his then partner Marijke Koger) who designed clothes, murals and record sleeves, including the Incredible String Band's eradefining The 5000 Spirits or the Layers of the Onion.

Ferris and The Fool, who collaborated on various images, first met in Ibiza in 1966. At this time Ferris was a fashion photographer.

"I started out working for teenage magazines like Petticoat and 19, then graduated up to She," he recalls. "Then I started to get quite a few shots in the Sunday Times and some pictures in Vogue."

During National Service with the RAF from 1959 Ferris had flown in Hawker Hunters, taking the photographs which monitored the accuracy of bombing practice. Having been to Vancouver while training, he returned there after leaving the RAF and apprenticed himself to a Norwegian-Canadian commercial photographer who let him take on the fashion assignments.

He arrived in Britain just as the profession of fashion photographer was taking on a new glamour.

When I suggest he was living a parallel life to that of David Hemmings' character in Antonioni's 1967 film Blow Up, he reveals that Antonioni actually visited his studio.

"The story there is that he went to a few studios," he adds.

"The photographer that character was mostly based on was David Bailey."

From fashion, it was a natural step into the pop music world.

"I was working with all these models, and who did they go out with but young pop stars. One of them, Charlotte Martin, was a girlfriend of Eric Clapton and she introduced me to Eric. Cream were recording Disraeli Gears at the time and he said they wanted something different in their promotional photographs."

The photographs in the St Paul's Gallery exhibition show the band posing in psychedelic finery with instruments decotraed by The Fool.

Another model, Jenny Boyd, younger sister of George Harrison's then wife Pattie Boyd, brought about an introduction to the Beatles during the Sgt Pepper sessions.

"I had already hooked up with Donovan, who was working in the small studio at Abbey Road, and I went there about three or four times," says Ferris. "It culminated in a big party when they were recording the last chord for A Day in the Life. The orchestra were dressed up in funny hats and funny noses and Paul was conducting them.

"There were cameras lying around on a table and George said 'Do you want to take some pictures? The only thing is, you have to put the camera in this box afterwards'. So I took some pictures and I also shot some 16mm movies. That stuff was put in a box and forgotten about, but a few years ago when the Beatles' Anthology came out I saw some of my 16mm footage."

Ferris had begun experimenting with colour photography at a time when the photographic world was inclined to be sniffy about it. The stylish look of the early 60s was high-contrast black-and-white of the kind epitomised by Robert Freeman's cover for With The Beatles.

"In those days it had to be black-and-white to be taken seriously, but I thought I would have a go at doing something artistic in colour, working with filters and gels.

"I was doing that for quite a while and putting it through the Kodak labs in High Holborn.

"The lab management said 'What's going on here? This is quite unusual stuff.' So I said I was messing around with colour and they asked if I would like to do a show with them - they had a gallery downstairs."

This led to the lucky break which enabled Ferris to invent "psychedelic" photography.

"They pointed out that they had this infra-red colour film which had just been released off the secret list.

"It had previously been used in spy planes like U2s. It could detect camouflage because what looked like a tree from above would be shown as a dead area because it picked up live foliage.

"They wanted to find a use for it, so they gave me a couple of cases to experiment with.

"I started with that, did tests on it, and got lots of garbage back with very unpleasant skin tones. I tried filters and messed around with processing times and started to get images where you have pleasing skin tones but the other colours are very wigged-out.

"So funnily enough it had been used for this very uptight, military use and I used it for psychedelic photography."

Actually it's not as ironic as all that, when you consider that LSD, the mind-liberating drug at the centre of the psychedelic experience, had figured in covert mind-control experiments launched by the CIA as early as 1950.

Both Ferris and Posthuma are keen to point out that pre-hippie drug-taking was not the escape from reality it later became.

"It was taken for mind-expanding purposes, to get outside the box and expand your ceativity," says Ferris. "This was going on in 1965-66 and originally it was serious stuff. Later on came the people who copied, and that's where it got the bad name."

Posthuma adds: "We took drugs to get more serious."

Originally an abstract painter, Posthuma travelled around Europe and North Africa with Koger in the early 1960s, arriving in Ibiza ("a fantastic place then, just a little fishing village, not the hedonistic place of today") after an exhibition in Madrid in 1963.

"From there we went to London. Everybody wanted us to do things for them - the Incredible String Band, Cream, the Hollies - and we worked with Karl Ferris.

"One day the Beatles knocked on my door. John and Paul rang the bell in St Stephen's Gardens. I opened the door and said don't I know you from somewhere?

"They laughed and came in and saw all our work.

"We had made this wall called 'The Wonderwall'. That was how the word was coined. John said 'I want to live in it'.

"This was the first psychedelic art."

The best-remembered link between The Fool and the Beatles is the mural they painted on the notorious Apple boutique, familiar from photographs of the time although the mural itself was shortlived.

With the addition of two more members, The Fool also briefly became a band in its own right. With its two-couple line-up, the image on its eponymous album's cover suggest a kind of proto-Abba.

As the end-of-decade moment brilliantly evoked in the classic film comedy Withnail and I kicked in, neither Ferris nor The Fool chose to hang around in London.

Ferris eventually made his way back to Vancouver, where today he is a film producer.

He is currently in the middle of making a feature-length documentary about the 60s counter-culture, called Revolution, which as the survivors head towards their 70s may prove to be the last definitive word on the subject.

"We've already done 100 interviews and we're going to do Donovan here," he says.

"We went to the Monterey Pop Festival 40th anniversary and were on stage with The Grateful Dead. By the time we've finished we'll have 125 to 130 interviews."

Posthuma and Koger moved to America, where Raquel Welch modelled their clothes and they painted a huge mural on Sunset Boulevard.

Marijke settled permanently in California, but Simon returned to to Holland in 1982 and picked up his career as a painter. He lives in Amsterdam with his 14 year-old son, a talented boogie-woogie pianist.

"Marijke and I were together for 12 years, but we had no children, unfortunately. Today I have a great studio in Amsterdam and now I'm just painting, like I used to."

So you might say the whole psychedelic adventure was really a diversion from his main career?

"An odd diversion from my career: you put that very well. There's a main route and an incredible scenic route - an alternative route."

* The Karl Ferris Experience is at the St Paul's Gallery, Northwood Street (near St Paul's Square) until October 6 (Tue-Sat 10am-6pm; admission free).