Man-made mayflies with a lifespan of just two weeks, the towering constructs of sculptor Gerry Judah’s imagination have dominated the lawn of Goodwood House at the Festival of Speed for the last 18 years.

Judah says: “I have to make a sculpture within a very short space of time, within a tight budget, that’s got to be as high as possible, as innovative as possible, as original as possible, and as dangerous as possible.

“Each year I like to think of something that’s very different to anything we’ve done before,” he adds. “The hardest thing about designing these sculptures is trying to avoid any conceptual connection with that which I’ve done before. You have to break that connection, yet retain an overall spirit to the work that gives some sort of continuity.

“It’s an intuitive process; you have a notion about what you want to say and how it relates to the space. But recently we’ve seen a lot of design approaches already made by the client.” Indeed, and, lighting 25 candles on the MX-5’s birthday cake, this year’s “Featured Marque”, Mazda, is no exception.

The germination of this year’s sculpture began decades ago with a present to Ikuo Maeda, Mazda’s chief designer, while a student: Danese Milano’s Ameland paper knife, designed by Enzo Mari. It took pride of place on Maeda-san’s desk, and he remained mesmerised by the elegant curvature of the design.

The Japanese have a word for it – shinari. This describes the powerful yet supple appearance of great resilient force when objects of high tensile strength, such as steel, are twisted or bent, or a person or animal flexing its body in preparation for a fast movement, such as an athlete about to leave the starting blocks.

In 2010, shinari duly spawned the company’s new design philosophy Kodo – Soul of Motion.

“It was Kodo that inspired the original idea behind the sculpture,” says Mazda’s design director Kevin Rice. “Breathing life and motion into an object is what Kodo is all about.

“This is how the whole body of the new MX-5 was created. Obviously, creating a 40-metre version of an MX-5 body side would be technically impossible and heavy beyond belief. So, Gerry’s idea of splitting the surfaces into strips gave birth to the ingenious ‘Kodo Lightweight’; a direct link to the quest Mazda set itself to reduce the MX-5’s weight.”

Judah explains: “I started to play with hundreds of ideas based on our discussions to do with twisted metal forms; trying out version after version until I came up with just a very simple twist, promptly leaving me with the age-old problem of how to make it work. I’m always faced with having to build in steel at Goodwood. I can’t do glass, I can’t do aluminium, I can’t do paper.

“The Mercedes, Lotus and Porsche sculptures were monocoques in which the skin itself was the structure; flat sheets of steel welded together to create a shape. But to do this piece in the same way, we’d have to twist each individual steel plate, which would be impossibly complex, time-consuming and expensive.

“I’d love to have made this piece in wood. Sadly, using timber would have been phenomenally expensive and hugely heavy. So we were faced with having to take the material properties and values of steel, and make it look like something else. And that’s how this idea developed.”

Any more detail would give the game away. But I can tell you that the completed sculpture is 40 metres long, rising to 36 metres above the ground. It weighs 120 tons; equivalent to more than 120 Mazda MX-5s. And laid end to end, the 418 steel tubes of which it is constructed would stretch 1,200 metres; the length of the Goodwood Festival of Speed hillclimb course.