It is my impression that, when the accusation of lying is thrown about during political debate, nine times out of ten what has actually happened is either that someone has said something which is wrong through a silly mistake or a failure to listen properly rather than a deliberate lie, or that two people have views so diametrically opposed that they cannot understand a sincere person holding the opposite opinion.
The third is that regular and frequent accusations of bad faith and lying are examples of the type of conduct which is coarsening political discourse in Britain and around the world, making constructive debate more difficult and driving decent people out of politics.
In my time in politics I've been called a liar when I was telling the truth more times than l could keep track of and there are few things more annoying. So I try very hard not to do the same thing to anyone else. If you search this blog or the rest of my social media output, you will find very few cases of my accusing any of my political opponents of lying.