As I said, bias is in the mind of those of a different view
Thatcher thought the BBC was biased against her and threatened to sort them
Blair thought the same and threatened the same
It's also in how they probe their questioning to force a response that meets their biased agenda. If it was questioning in court it could be called leading the witness like putting words in their mouth.
Personally I think Question Time need completely scrapping. It's all faked with a prearranged audience that suits their agenda and questions already set out and ministers have time to prepare answers, not that they answer any and it all turns onto more of a bickering match. Fiona Bruce is no Angela Rippon.
QT was at its best when Robin Day was in the chair. He wasn't at all biassed. He was rude to everyone!