Boris Johnson once boasted that you couldn't hold a cigarette paper between him and David Frost, the man he brought on to take Brexit over the line. Yet this key ally has resigned when the Prime Minister is at his most vulnerable. In his resignation letter, Lord Frost cites his concerns on whether the country is making the most of Brexit to cut taxes and red tape, and the direction of travel when it comes to dealing with the pandemic. On the podcast, Katy Balls talks to Fraser Nelson and James Forsyth about the significance of this moment – which Fraser says is 'a bigger blow to the Prime Minister than the by-election'. Taking a look at his reasons for departure, James says 'All the reasons he is citing – high taxes, Covid passes, net zero – punch every vulnerability that Boris Johnson has with the Tory activist base'.