This is worse than countries such as Germany and France, where it is forecast to fall 0.9% and 4.7% respectively, year on year. GroupM's outlook is gloomier than Carat's, which was issued in late March. Carat said UK ad spend would fall 7.1% year on year in 2009.
The Aegis media agency then expects UK ad spend to return to growth in 2010, with a 2% increase - far ahead of its peers.
France is forecast only to post 0.5% growth in 2010, while the US is expected to decline 2.7% in 2010.
Regionally, according to GroupM's latest forecast, media spend in Western Europe is expected to fall 8.5% this year, lower than the 18.1% expected in Eastern Europe, but worse than the 6.8% decline predicted in Asia-Pacific.
Meanwhile, it is expected that ad spend in North America, which fell 3.4% last year, will drop by almost double that amount in 2009, to 6%.