MarketingDigital ad spend growth slowed to 5% in 2020, says IAB UK Kristaps Safranovs / May 3, 2021 The Interactive Bureau of Advertising UK (IAB) has said UK digital ad spend growth slowed to 5% in 2020 to reach a total of £16.5bn. The report, produced with PwC, looks to define spend in a year like no other. Source