Looking carefully at an angular steel sculpture from 1963, three years before his breakthrough exhibition at the Whitechapel Gallery, Bryan Kneale remarks that he can finally see where it came from - a memory of a mechanical wonder from his childhood on the Isle of Man.

“There used to be a curious sort of amusement park. We’re talking about the 1930s… you crossed the harbour on a funny little paddle boat, and then one of the delights you could have on the other side was being weighed on a huge brass scales,” he recalls.

“I think you won a prize if people guessed your weight… and I think that’s probably where that came from. I’ve always been extremely interested in the way things go together.

“It could also be connected to a folding slide I made for my daughter Kate when she was one. In making it, I became very interested in the way things fold shut and open up again, so I decided I would make a folding sculpture. It tied in with so many other things.”

One of the key figures in 20th century British sculpture, Kneale - the first abstract sculptor to be elected an Academician - also played a pivotal role in changing the Royal Academy from an organisation seen by many as the enemy of the avant-garde, to one that began to open its doors to a new generation of artists.

Told that he had been elected an associate of the Royal Academy in 1970, he refused to accept unless the Academy mounted a major show of contemporary British sculpture. The resulting exhibition - British Sculptors ’72 - was curated by Kneale and featured artists such as Eduardo Paolozzi, Phillip King and Geoffrey Clarke, who went on to become Academicians themselves.

Kneale’s connection with the Royal Academy began much earlier, however, when he joined the RA Schools at the age of 17. To begin with, he was primarily a painter, not least because of the “remoteness” of sculpture as it was then taught in art schools.

“If you went into a sculpture school like the one at the Royal Academy in the ‘40s, it consisted of a nude model sitting in the middle of the room, with the students going up and measuring [the model]… it all looked rather sinister if you ask me! They then transposed their measurements to a clay model which took forever to do. Then came the process of casting in plaster, which equally was a very long and tortuous process. Finally, they would paint the plaster to look like bronze. They were frightfully good at it, it looked like bronze, too - except that it was plaster, and highly fragile.

“I knew that this simply was not for me. I needed to be able to, as they say, let the dog see the rabbit. It was probably part of my personality, and partly because I was used to a direct method of painting and drawing, that I had to find a way of making sculpture which had the same sort of speed. I wanted to see what I was doing, and I didn’t want a process which was too remote.”

Ill health in recent years has meant Kneale’s hands-on approach to sculpture is no longer possible, but he continues to draw and work on other projects. Drawing has always played a key role in his artistic practice.

“The Summer Exhibition is looming, and I intend to show in that. I’ll probably be doing some drawings. I’m very fond of showing in the Summer Exhibition, because it’s something I’ve done every year since I was student at the RA in the late ‘40s.”

Bryan Kneale: Five Decades is at Pangolin London until 2 May 2015.