Bill Bernbach, a founder of the DDB advertising agency and widely regarded as father of the modern marketing industry, once said that advertising “is fundamentally persuasion and persuasion happens to be not a science, but an art”.

Brands spend more than $540bn worldwide on advertising, according to eMarketer, the research company. Yet marketing is increasingly grappling with significant problems. Whether reaching millennial consumers who want to escape marketing messages, or “cord-cutting” television viewers, who ditch cable and satellite subscriptions in favour of ad-free Netflix, advertisers are having to work harder than ever to find their audience.

Technological change has made the task harder still. Ad blocking software has created real problems for digital publishers reliant on display advertising. Ad fraud is a similar worry, with the World Federation of Advertisers, whose members include McDonald’s and Unilever, recently warning of “endemic” digital ad fraud and claiming that up to 30 per cent of all online ads are never seen by real humans. The WFA is forecasting industry revenue losses of $50bn by 2025 unless marketers take immediate and effective action.