Stephen Fry, Chrissie Hynde and Sophie Winkleman are among the celebrities and concerned London residents who have signed an open letter protesting TfL signage that promotes 4G on the Tube.The letter calls for removal of a poster that shows a young woman looking at her phone with the caption “5G is coming to the Tube”.The message, which is spearheaded by musician and Save Soho founder Tim Arnold, warns of the “potential dangers” of this advertisement and references the UK Code of Broadcast Advertising.Said code advises that “advertisements must not condone, encourage or unreasonably feature behaviour that could be dangerous for children to emulate.” The letter implies that the TfL 5G advertising breaches this code.