'DO I believe that the use of computer-based technology results in a lack of emotional impact in modern design?" grins Storm Thorgerson, taking a sip of red wine and thinking hard, as he often does, before speaking.
"One of the main problems with contemporary computer-based graphics is the plethora of 'wallpaper' designs that are pretty, tasteful, discreet, selectively focused and smeared, but they're not idea-driven. Although there is a view that visual design has no need, perhaps no place, to be idea-driven, it clearly isn't my view. Some computer stuff is very nice but that's what it is... very nice. It titillates the retina, but moves the heart or tells the head very little."
Thorgerson, on the other hand, uses a mesmerising mixture of fantasy and reality, creating the sort of surreal images which are crystal clear yet somehow utterly confusing. Since he started in 1968 there has always been a sense of mystery to his work.
We are having lunch in a restaurant beneath his Belsize Park studio, which he has owned since the early 1970s. From the moment we start to talk it becomes clear there is nothing remotely conventional about him. It may be lunchtime for Thorgerson but for everyone else it is 5pm. Having suffered a stroke a few years ago his physical movement is limited but he is still positively fizzing with enthusiasm for his work.
Born in 1944 in Potters Bar, Thorgerson's childhood would not have been considered unusual were it not for the fact that he went to school in Cambridge with Pink Floyd founders Roger Waters and Syd Barrett.
"Roger and I had two connections, one of which was through our mothers, who happened to be pals, and also because we tended to play rugby and cricket together at school, so we knew each other in that context before Pink Floyd. Syd was just one of the gang and at that time there had been no herald of his artistry.
"If I hadn't known the Floyd then I'd probably have done something else, if not better. Sometimes the Floyd might say 'We think you owe your career as much to us as we do to you... or more. Well, I wonder."
Having studied English and philosophy at university, inspired by seeing Fellini's 81/2 and Antonioni's L'Avventura, Thorgerson completed an MA in film and television at London's Royal College Of Art. Floyd had already enjoyed success with their debut album, Piper At The Gates Of Dawn, and were putting the finishing touches to their second, A Saucerful Of Secrets, when a friend turned down the job of creating its sleeve. With no background in art or graphic design, Thorgerson volunteered.
"They happened to be in our flat and they asked David Henderson, who was a painter, but he refused," he recalls. "I was nosily listening at the door and I said 'I'll do that'. I took a chance that was in front of me. I didn't know any better really. They didn't know any better either, and they just said 'Oh, okay then'."
By the time Floyd started recording their next album it was clear that Barrett - until then, the charismatic leader of the band - wasn't mentally fit enough to continue. They had no choice but to part company with their frontman, who soon spiralled out of control and disappeared into a mental fog that kept him hidden from the outside world until he died three years ago.
Along with friend Aubrey Powell, Thorgerson formed a graphic design company, Hipgnosis. Their surrealist work raised the bar for album-cover design and changed the way the world looked at music through their sleeves. Hipgnosis designed covers for everyone from Paul McCartney and Peter Gabriel to Black Sabbath and Led Zeppelin. More recently, Thorgerson has worked with an eclectic array of artists including Muse, Anthrax and The Cranberries.
In the current climate where every image seems to have been generated through a computer, the most astonishing thing about Thorgerson's work is that he has painstakingly set up most of his album cover shoots for real.
From the burning businessman on Wish You Were Here and the inflatable pig over Battersea Power Station on Animals to placing 700 wrought-iron beds on a beach in north Devon for A Momentary Lapse Of Reason, Thorgerson could never be accused of cutting corners.
"What price art, eh? We put a cow on the cover for the Floyd's Atom Heart Mother so it probably cost about a tenner, but you could have bought a house for the cost of A Momentary Lapse Of Reason. When we did that one it kept raining so you couldn't really see that all those beds were actually there anyway, and we had to take them all back again and repeat the whole exercise two weeks later. At that point, I wondered if I was stark raving mad," he laughs.
What does Thorgerson remember about shooting the sleeves for Wish You Were Here and Animals? "One of the main things I thought about 'Burning Man' is it's a bit scary - this idea that you might actually set a man on fire for a record cover, which is a bit like - next step, snuff movies - so what will you do for your art? Obviously, in 1975, people knew that it was real, so they were saying 'How did they do that?' and 'Did the man actually die?' Art has often bordered on the sort of showmanship edge.
"I remember the Animals cover shoot being a total hoot. Roger was very fond of Battersea Power Station and they had this gigantic inflatable pig that was part of the Floyd live show. We couldn't get the pig airborne and then it escaped from its moorings directly into the flightpaths of Heathrow airport. You couldn't have paid for all the newspaper coverage it got at the time: 'Airline Pilots See Flying Pigs.' I think Pink Floyd had their share of daft Spinal Tap moments and this was one of them."
Thorgerson designed almost every Floyd album sleeve from A Saucerful Of Secrets onwards, although it is his work on 1973's The Dark Side Of The Moon that left the most indelible mark on the cultural landscape. His prism design has mystified and mesmerised fans ever since.
"The idea was cobbled from a standard physics textbook, which illustrated light passing through a prism," Thorgerson explains. "Rick Wright suggested we do something simple, elegant and graphic, not photographic. We decided to connect it to ambition and madness, which were themes Roger was exploring heavily in the lyrics... hence the prism, triangle and pyramids. Somehow, it all connects. The design meeting took about three seconds. The band cast their eyes over everything, looked at each other and said 'That one'.
"Part of the creative process is like a little mental journey. Most of it takes place at the beginning - the conceptualising or the imagining of the ideas. So it's that which is like a flight of the imagination, and it's very pleasurable indeed."
Thorgerson discusses his work and the creative process at the Connecting Conversations event at London Metropolitan University, Holloway Road, on July 3. The event is part of the Holloway Arts Festival.