Gary Lineker is a brilliant presenter, and by all accounts a good man who cares deeply about the underdog. He is not on the BBC staff and not a news journalist, and so is not bound by that part of the BBC’s impartiality guidelines that says:
BBC staff and regular presenters or reporters associated with news or public policy-related output may offer professional judgements rooted in evidence. However, it is not normally appropriate for them to present or write personal view content on public policy, matters of political or industrial controversy, or “controversial subjects” in any area.
