The rise marks the ninth year of market growth and the highest level of spend since monitoring began in 1982.

The fourth quarter of 2018 was particularly strong, according to the report, with spend reaching £6.5bn, an increase of 5.7% compared to the final quarter of 2017.

Growth was driven by clients increasingly spending on search (up 14.3%) and online display advertising ( 21.4%), while online radio advertising grew by 30.6%.

Spending contracted on direct mail (down 8.5%), regional newsbrands (-9.3%), national newsbrands (-6.3%) and cinema advertising (-2.1%).

James McDonald, managing editor at Warc, said: “Despite most traditional media being stagnant or in decline, the UK’s ad market expanded at its strongest rate since 2015 last year, and the growth is primarily being driven by rapidly rising investment in paid search and online display formats, particularly social media and online video.

“These online components account for just over half of UK advertising spend today, and both are almost entirely data-driven, enabling advertisers to pair their messaging with internet users based on their digital footprint.”

AA and Warc have changed their forecast for 2019 ad spend to £24.7bn, which would be a 4.8% growth.

Stephen Woodford, chief executive at the Advertising Association, said: “These figures demonstrate, once again, the strength and resilience of the UK advertising industry during a time of political and economic uncertainty.”

The report launched online in February 2010 and combines data from the discontinued print publications the Quarterly Survey of Advertising Expenditure and the Advertising Forecast.