United Kingdom: How much will former UK PM Boris Johnson earn after office?

It was called Boris Johnson's longest goodbye, one scandal after the other nothing seemed to shake him until his own party members lost faith in him. As he is all set to exit the 10 Downing street, there is one question that remains - How much is Boris Johnson going to earn after he leaves office? Well, he might earn far more than how much he was getting as a UK PM!