EssenceMediacom, WPP Media

As the biggest agency in the UK, more clients choose to work with us than anyone else - by a large margin. Behind being the most chosen is a client obsession that we live every day. We provably solve age-old problems and knotty issues that clients have been grappling with for years, through new tools and research projects. We deliver more diversified services to our clients than any other media agency in the UK, from product placement to creative idents and econometrics. And we go out of our way to uncover new findings about how media works, to the benefit of not just our clients, but everyone else’s too. This year we grew for the 13th consecutive year, which as the largest agency - twice as big as the next competitor - is not easy.