Lord Frost has taken chunks out of Tory leadership frontrunner Penny Mordaunt in a blistering interview in which he said he had “grave reservations” about PM becoming PM.

The former Brexit negotiator went for the jugular, criticising Mordaunt’s performance when she worked as his junior haggling over the divorce from the EU.

“I’m sorry to say this, I felt she did not master the detail that was necessary when we were in negotiations,” Lord Frost told TalkTV, attacking her Brexiteer credentials. “She wouldn’t always deliver tough messages to the EU when that was necessary.”

Mordaunt voted for Theresa May‘s Brexit deal, a heretical act in the view of many hardened Brexiteers, as Frost has become. Could this lie behind the attack? Or might the two have had a falling out? In any case, Frost is a marmite figure, and his vitriol might be seen as a badge of honour by Penny supporters who think he’s got too big for his boots.

Frost added that Mordaunt hadn’t been accountable or visible when she worked in his department: “Sometimes I didn’t even know where she was.” Ouch.

Watch the full mauling here: