John Kearon thought the software would take four months and £40,000. It took two years and roughly £400,000. He paid for development with savings and consultancy work, keeping one business going so that another could exist. For someone building a career around the fallibility of human judgement, this was an unusually thorough piece of fieldwork.
The idea became BrainJuicer, later System1. Its founder wanted companies to understand people through something more useful than the polished explanations people offer about themselves. He would spend years arguing that a feeling could tell an advertiser more than a carefully considered answer. First, though, he needed somebody to buy the software.
Nike did. A modest project collecting feedback on its Run London event gave Kearon something the invoice alone could not supply: confidence that an unfamiliar approach had a customer. The early product used open questions and a more conversational way of engaging respondents. A sports brand had seen the point. The next task was persuading the research business.
The first prediction he had to revise was his own.
A corporate education in rebellion
Kearon came from the world he would later challenge. He studied at Birmingham, began his career at Unilever in 1986 and worked in advertising planning at Publicis/FCA before starting the innovation agency Brand Genetics. He had experienced the corporate machinery around a product: the research, the marketing and the effort to make an idea acceptable.
Brand Genetics gave him a particular puzzle. Large businesses had money, people and established brands. Why did they so often struggle to invent the unfamiliar things that smaller companies brought to market? He became interested in using internet software to change the pace and character of research. The company behind BrainJuicer was incorporated in December 1999; he dates the venture’s launch to January 2000.
Unilever Ventures backed the business in 2003. His former corporate world had become part of the experiment. By 2005 BrainJuicer had offices in the Netherlands and New York. Winning Philips as a global concept-testing client gave the little company another reason to believe it could compete beyond Britain.
The early story has the familiar ingredients of a technology business, including a development budget that behaved like a suggestion. But Kearon’s deeper preoccupation was with the questions clients asked. Moving a questionnaire onto a screen could speed up the process. He wanted to change what the process valued.
The questionnaire meets a feeling
In 2011, asked which research methods he would buy or sell as investments, Kearon treated the exercise as an invitation to clear out the cupboard. Conventional testing and tracking came under attack. He favoured prediction markets, observation and research that placed people closer to the circumstances in which they actually made choices.
His objection was to the distance between a tidy explanation and a messy decision. Ask somebody to justify a preference and you may receive a convincing account. Whether that account predicts what they do is another matter. His commercial proposition rested on finding measures that better connected the response to the eventual behaviour.
System1’s approach makes that argument practical. People viewing an advertisement select how they feel from a pictorial scale representing seven emotions, with neutrality available too. The viewer reports the feeling. An algorithm does not have to infer it from a face. The distinction matters when the business being discussed is routinely described as measuring emotion.
The company relates those responses to commercial outcomes. Its methodology includes a 2009 exercise in which campaigns with known business results were tested blind; Peter Field analysed the relationship using the IPA Effectiveness Databank. Kearon’s wager therefore demanded more than an attractive theory. It had to survive comparison with what happened in the market.
A simplified explanation of the company’s stated method.
Success, with a slightly ridiculous name
BrainJuicer floated on London’s AIM market in 2006. The name supplied its own small act of resistance. A research company could sound playful and still submit to the obligations of a public listing. Kearon’s title, Chief Juicer, ensured that nobody mistook the mood for that of an insurance office.
Recognition followed the methods. He received EY’s Emerging Entrepreneur of the Year award in 2005 and the London regional Entrepreneur of the Year award in 2009. The Advertising Research Foundation recognised him as a research innovator in 2008. BrainJuicer won ESOMAR methodology awards in 2005 and 2007.
By its fifteenth birthday, he said the company was conducting research in more than 70 countries. The campaigns he was proud to have helped clients with included Three’s moonwalking pony and John Lewis Christmas advertising. His examples were entertainment people remembered, rather than product benefits recited with admirable concentration.
He also named his influences with pleasingly little regard for departmental boundaries: Brian Eno, the Chapman Brothers, James Dyson, Mark Earls and Rory Sutherland. Music, art, design and marketing shared a place in his account of where useful provocation came from. A person who wanted a reassuring industry consensus had picked an inconvenient set of heroes.
“How often the safety net appeared when we took a leap into the unknown.”
John Kearon, reflecting on entrepreneurship in 2015
An April Fool’s Day with consequences
On 1 April 2017, BrainJuicer became System1. The date invited the obvious suspicion. The change itself was deliberate: the company adopted the name of the fast, intuitive mode of thinking that sat at the centre of its argument about decision-making. The research business and its creative agency would now share that identity.
Renaming a business with an established reputation asks clients to learn something new. In this case, the name also made the company’s position harder to miss. An advertiser could disagree with the premise, but the premise was printed on the door.
That year, Kearon, Orlando Wood and Tom Ewing published System1: Unlocking Profitable Growth. It carried the argument into innovation, advertising, branding and shopper marketing. A book offered more room than a sales presentation to explain how a view of human choice might change the work.
Kearon took the discussion to Parliament in November 2017. Giving evidence on advertising, he questioned the industry’s excitement about digital media and argued for judging film by its effect and the cost of reaching people. The setting was formal; his instinct remained to challenge what everybody seemed to be accepting.
The audience includes the people at work
The argument about feeling extended beyond advertisements. Kearon has spoken about enjoying work, valuing playfulness and resisting the assumption that a job is something dull to endure until retirement. At his 2011 DO Lectures appearance, his subject was why companies should make people feel something. It was an argument well suited to a speaker willing to make an impression himself.
Alex Hunt, who joined the American business in 2009, remembered considering an MBA. Kearon encouraged him to join and learn through the job instead. Hunt became the fifth US employee. The invitation captured the attraction of an expanding company where commercial education came attached to actual customers.
In his 2017 parliamentary evidence, Kearon was relaxed about graduates moving on after several years. He wanted them to leave feeling good about the company. He also advocated mixing people between international offices. Learning, in this account, involved exposure to other people and places rather than simply accumulating qualifications.
There was a charitable expression of that outlook too. He became president of the ESOMAR Foundation in 2017. During his presidency, its work included scholarships and support for researchers facing crises. Its 2024 report recorded 22 scholars funded over the programme’s history. Those outcomes belonged to a team of donors, volunteers and board members; his role placed him among them.
The founder learns to be number two
James Gregory succeeded Kearon as CEO in December 2022. For a founder whose personality had long been attached to the company, the transfer involved more than a title. Kearon later described making sure employees understood who was now in charge and resisting the impulse to direct the business from the passenger seat.
He spent time developing the US business and returned to invention through System1 Futures. In his 2025 retrospective, he described a future in which the company’s intellectual property could support a billion-pound business. That was an ambition, rather than a statement of its size. It also located the next stage of growth with Gregory’s leadership.
From September 2025, Kearon moved into a non-executive role and chaired a strategic and product advisory committee. The progression gave the founder another way to contribute. Then, in March 2026, he made a more decisive change.
He exchanged his roughly 23% System1 holding for shares in Brave Bison. Brave Bison’s investor register, updated in July, listed him with an 8.4% interest. System1’s annual results marked his departure as both a director and a direct shareholder. He remained economically involved through a different company.
By October 2026, Brave Bison’s attempt to acquire the rest of System1 had become contested. On 15 October, System1’s board again recommended rejecting the offer and reiterated that Kearon no longer had operational or executive involvement. The distinction gives the present-day portrait its necessary edge: the founder and the company he created now occupy different positions in a negotiation about its future.
There is a pleasing difficulty in Kearon’s story. Someone who built a business questioning rational explanations has had to face very concrete judgements about cost, leadership and ownership. His work keeps returning to the same demanding question: what do people actually respond to? After the questionnaires, the books and the boardroom changes, he has left advertisers with an awkward possibility to consider. Their audience may remember the feeling long after it has forgotten the argument.