Drinks giant Diageo was the biggest out-of-home advertiser in Ireland in 2013, according to a new report by media agency PML Group. The company, which counts Guinness and Smirnoff among its brands, increased its spending in the second half of the year as Arthur's Day and Christmas prompted outdoor campaigns.

Diageo accounted for 4.1 per cent of all advertising displayed on billboards, transport posters, digital screens and other formats last year, in what was the busiest year for out-of-home advertising since 2008, PML’s Posterwatch review of the sector found.

Household goods group Unilever was in second place, followed by Cadbury-owner Mondeléz, which PML Group said was "probably the most consistent out-of-home advertiser in 2013" along with the fifth-placed McDonald's.

Eircom was the fourth most active advertiser thanks to campaigns for mobile brand Meteor and its broadband and business products. Telecommunications was also the top-spending sector, with O2-owner Telefonica, Vodafone and Sky also ranking among the heaviest advertisers.

Telecoms companies “had a substantially larger presence throughout the year than any other group”, PML said, accounting for 12 per cent of out-of-home advertising in 2013. It was the top-spending category across all four quarters.

PML estimates that out-of-home advertising grew 8 per cent last year, as it bounced back from a subdued 2012. Banks, led by Bank of Ireland, were among those that returned with highly visible campaigns. However, beer and cider advertising declined as Heineken and Bulmers reduced their investment in the medium.

Company rivalries had a positive impact on the market, PML Group said. “Categories such as mobile telecoms, television and internet providers, banks and radio stations often reacted to competitors’ out-of-home campaigns with one of their own.”