Global rely on large ad groups for a major source of its revenue - Mike Kemp/In Pictures via Getty Images Billboard operator Global has been criticised after pulling a campaign that mocked major advertising agencies. Senior executives at Global, which operates more than 250,000 billboards next to roads and on the London Underground, intervened to pull a paid campaign that poked fun at ad giants such as WPP after it had already launched. The media company told WeAreSPQR, the PR firm behind the campaign, ...