Media buying network ZenithOptimedia has halved its TV ad revenue growth forecast for the UK in 2012, while predicting digital spend will rise by £200 million. ZenithOptimedia, part of Maurice Lévy's Publicis Groupe, is forecasting year-on-year growth of just 0.5% in the UK television advertising market this year to £3.3 billion. The media buying network's revised forecast follows widespread concern that advertiser sentiment has failed to follow predictions of a "summer of love" for commercial broadcasters and other media owners from events such as the London Olympics.