Sunak should see Mordaunt as a threat after her scathing opening debate remarks despite otherwise on message performance

It was reported last weekend that allies of Penny Mordaunt claimed Downing Street was keeping her "in a box" during the election campaign because Rishi Sunak's team see her as a threat.

Well, after her barnstorming performance in a TV debate against politicians from six opposition parties, the Leader of the Commons is well and truly out of her box now. And she mustn't be put back in it.

Her opening words in this 90-minute showdown were explosive. The prime minister, she declared, was "completely wrong" to leave the D-Day ceremonies in Normandy early. No pulling of punches there.

She said the PM was wrong, not once, not twice, but three times. No wonder Number 10 see her as a threat. If this was an audition for a leadership bid after the election, her friends will claim she passed with flying colours.

But once she'd finished her scathing opening remarks, Mordaunt was relentlessly on message in hammering Labour on its policies on tax, immigration and crime.

She was at her most combative on the Tories' controversial allegation - first made by Sunak in his TV debate with Sir Keir Starmer on Tuesday - that Labour is planning a £2,000 per household tax grab if it wins the election.

This attack triggered the most heated clash of the whole debate as Mordaunt traded blows with Labour's Angela Rayner on tax. It was a shouting match that went on long after presenter Mishal Husain attempted - but failed - to stop them.

It was all the more heated because the pair were standing next to each other at the end of the row of seven leading politicians - alongside Reform's Nigel Farage, the Lib Dems' Daisy Cooper and the SNP's Westminster leader Stephen Flynn, Plaid Cymru's and Rhun ap Iorwerth and Carla Denyer, from the Greens.

For the rest of the debate, Rayner was slightly subdued, rather like Sir Keir had been against the PM on Tuesday. Rayner didn't even attack Sunak about D-Day at the start. Like Sir Keir, his deputy needs to raise her game.

Besides Mordaunt, on D-Day Farage claimed Sunak had been unpatriotic and Flynn accused the PM of putting his own political career before public service and Normandy war veterans. Strong stuff.

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Mordaunt also tore into Rayner over her previous voting record against renewing Trident. And the brightness of Rayner's red dress wasn't matched by a bright performance in the debate, although she improved as the debate went on. Mordaunt, incidentally, wore Thatcher blue. Remind you of anyone?

Throughout the debate, Farage was typically impish. His quips included claiming Starmer was "very dull" and "Blair without the flair". The PM, he joked, was "slippery Sunak". Yes, he's used those jibes before, but the audience enjoyed them.

Flynn had his good moments, most notably when he condemned Brexit, an attack on the Conservatives and Labour that the audience enjoyed.

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But this debate was about Mordaunt. It was her show, despite the large cast list. If she has been kept in a box by No 10 up to now, the PM's allies will have been delighted by her attacks on Rayner and Labour's policies.

But they won't have appreciated her blunt - and completely unprompted criticism - of the prime minister over the big story of the day, his D-Day snub.

It was a story about a blunder of the PM's own making. It wasn't a gaffe, or an accident. It was sheer bad planning, terrible political judgement, embarrassing and highly damaging to Sunak and the Tory election campaign.

That, apparently was, Mordaunt's view. And she said so. No 10 won't be happy. A threat? You bet.