Iain Dale presents the evening show on LBC Radio and is a commentator for CNN.

When Gavin Williamson told a meeting of Ministry of Defence top brass that he had “made [Theresa May], so I can break her”, I doubt whether anyone in that room – let alone Williamson himself – could have foreseen that it would actually turn out to be the other way around.

Indeed, at a meeting in Downing Street on Wednesday afternoon, the Prime Minister told her Defence Secretary to “shut up and go Huawei” – or words to that effect.

Ad yet another shooting star joined that growing club of Ex-Future Prime Ministers.

It was without doubt the most brutal sacking letter issues by an occupant of Downing Street in living memory. Williamson’s reply was more measured, but full of hurt and a total lack of comprehension.

He remains adamant he wasn’t the leaker, and has refused to go quietly. The trouble is that there are few people who believe him. Circumstantially, the evidence points to him as guilty as charged – but we should bear in mind that circumstantial evidence can often be wrong. Ask Peter Mandelson. Ask Amber Rudd.

But, first, Williamson did indeed have an eleven minute telephone conversation with Steve Swinford, the journalist who wrote the National Security Council leak story, on the day of its publication.  Second, his media advisor is a former Daily Telegraph Defence Editor. Third, Williamson has a long track record of being China-sceptic. Fourth, although he is notoriously camera and microphone-shy, he is an inveterate gossip and relishes confiding in journalists.

But none of that means he can be found guilty without firm evidence, and that seems to be conspicuous by its absence here.

I wrote a five thousand word profile of Gavin Williamson for the Sunday Times last December. I didn’t know him before I was commissioned to write it. What I found was an incredibly likeable person. He seemed utterly devoted to his constituency and clearly loved doing the job at Defence.

He did tell me at one point, though, that he had also loved being Chief Whip, and would go back to the post like a shot. He had worked out by that point what his strengths were, and he clearly realised that being Chief Whip was a job he was almost born to do, and was bloody good at, whereas maybe Defence didn’t quite fit him like a hand in a glove.

He missed being in and out of Number Ten. He missed being so close to the Prime Minister. He missed her asking his advice so much. In short, he missed being a player.

Over the last year, after recovering from several high-profile gaffes, he knuckled down at Defence and scored some victories. However, Downing Street officials persisted in tearing their collective hair out over his various pronouncements, and his pivot from Remain to Leave, and his increasingly robust pronouncements on Brexit in Cabinet left them perplexed.

His relationship with Theresa May had certainly cooled, according to insiders. Perhaps this made her decision to sack him a little easier than it might have been otherwise.

I am not sure we will ever get to the truth of what exactly happened. Swinford, in theory, could come to Williamson’s rescue, if the latter wasn’t indeed the source of the leak, but it would be highly unusual for a journalist to do something like that, and it would set what might become an unfortunate precedent.

The only other way for anything to be resolved would be for the police to conduct an inquiry, and this is where Labour should concentrate their ammunition. In my view, unless there is actual physical proof, a policy inquiry is unlikely to reach an evidential bar – but politically the issue is a gift for Labour.

As for Williamson himself, he should take some advice from Andrew Mitchell, who has been through something vaguely similar. In his case, he resigned protesting his innocence over ‘Plebgate’.

That seems rather trifling, compared to the issue of leaks from the National Security Committee, but there are some parallels to be drawn. The worst thing that Williamson could do is spend the next ten years brooding over what might have been. Out of threats come opportunities, and he would do well to think on that.

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Talking of opportunities, let’s turn to Penny Mordaunt.

I’ve always considered her a real dark horse to succeed Theresa May, and this promotion certainly won’t do her prospects any harm at all. I’m certain that the new Defence Secretary will stand – and she could well come through the middle as everybody’s compromise candidate. There’s a lot to be said for being everyone’s second choice.

Mordaunt is a Brexiteer, although she will have some explaining to do with the ERG since, like Michael Gove, Liam Fox, Andrea Leadsom and Chris Grayling, she has dipped her hands into the Chequers blood.  But she’s popular across the parliamentary party, and I suspect that the same would apply to the voluntary party – but they need an opportunity to get to know her. This job gives her the chance to enable them to do just that.