James Dyson

In 1978 he adapted the cyclone collectors used in sawmills to a household vacuum cleaner, testing more than 5,000 prototypes over about five years, according to Britannica. After established makers showed no interest he sold the design in Japan as the G-Force, which the Design Museum says funded his own DC01, made in Wiltshire from 1993 and, Britannica says, Britain's top-selling vacuum cleaner within two years despite a higher price.

He built Dyson beyond the vacuum cleaner: Britannica records the Air Multiplier bladeless fan of 2009, an Observer interview describes the company's Airblade hand dryer, and the Guardian reported in 2005 that, about two years after entering the American market, Dyson had become the most popular vacuum cleaner there, a claim the company announced; Cooper Hewitt dates the US launch of the DC07 to 2002.

The Royal Designers for Industry list him under Engineering Design (2005), and the Royal Society, which elected him a Fellow in 2015, says he holds 1,138 patents and funds 50 research projects at UK universities; his G-Force, DC01 and DC07 cleaners are held by the Design Museum, the Science Museum Group and Cooper Hewitt.

When Dyson's team began selling the cleaner with a see-through bin, retailers were appalled and said people would not want to see the dirt, and market research agreed. Dyson says he could not prove people would buy it but kept the design, and his design director Peter Gammack says colleagues were uncomfortable with the idea but that 'he stuck to his guns'; Dyson adds that other makers now use clear bins too.

This is consistent with a designer who backs his own judgement over market research, though both accounts come from Dyson and his own design director and are told after the product succeeded. Independent Thinking

On 10 October 2019 Dyson emailed staff that his team had built a 'fantastic car' but that 'we simply can no longer see a way to make it commercially viable'. He said he had tried to sell the division without finding a buyer, that this was not 'a product failure, or a failure of the team', and the company said it hoped to find other roles for most of the 523 people involved, 498 of them in the UK. A business-school professor told the Guardian the project had never stacked up commercially and looked like a vanity project.

This is consistent with a founder who stops a very large project when its economics do not work, though the decision came after he had confirmed a £2.5bn investment plan covering the car and an outside critic read the project as a vanity project. Belief Updating

Unable to find support for his bagless design in the UK, and with the established manufacturers uninterested, Dyson licensed it in Japan, where the G-Force went on sale in 1986 and, the Design Museum says, succeeded well enough to fund his own production of the DC01. He opened his own plant in North Wiltshire in 1993, and Britannica says the Dual Cyclone was Britain's top-selling vacuum cleaner within two years.

This is consistent with someone who built his own route to market when the existing ones were closed, though most details of the earlier rejections come from his own account. Proactive Agency