Theresa May can’t afford to lose Amber Rudd – which puts the home secretary in a surprisingly strong position

Sajid Javid as home secretary? The Westminster media pack in one of its frenzies is a wonder to behold. As the wait for a response from the Home Office to the leak of a memo stretched into its fourth hour yesterday, journalists were already gaming the next few moves.

If Amber Rudd resigned, who would replace her? And if it was Javid, as Paul Waugh of the Huffington Post suggested, who would replace him (possibly Liz Truss, he said). Would Rudd join the backbench rebels campaigning for a softer Brexit? What was the cause of the delay? Was there something else damning with which Rudd and the prime minister were wrestling?

Seven hours after The Guardian published the memo from June last year suggesting that Rudd should have known about the targets for immigration removals, the home secretary herself announced – on Twitter – that she would be staying in post. At least until Monday, when she would make another statement to the House of Commons.

Instantly, we could see what had always been true: that, as long as there aren’t any further damning documents, and there still could be, it is very much in the prime minister’s interest to keep Rudd where she is.

As Nick Watt of BBC 2’s Newsnight reported last night, “people who know Theresa May’s mind” are “absolutely scathing about Amber Rudd’s handling of the Home Office”.

The home secretary’s evidence to Yvette Cooper, my former colleague as a leader-writer on The Independent, now chair of the Home Affairs select committee, on Wednesday was certainly a remarkable moment. Cooper asked: “Targets for removals: when were they set?” Rudd replied: “We do not have targets for removals.”

The only credible explanations for her answer are that she thought her department did not have targets for removals, or that she thought the word “targets” meant something other than its plain English meaning.

I thought the birds in the trees knew that the Home Office had targets for removals. Cooper’s committee had just been discussing them at length with the head of the immigration service’s union. Rudd was told about the targets in the leaked memo, but says: “I didn’t see it.”

She herself had sent a letter to the prime minister (also leaked, last week) in January 2017 saying: “I will be reallocating £10m ... with the aim of increasing the number of enforced removals by more than 10 per cent over the next few years.” In plain English, that is a target.

But Rudd appears to think otherwise, and this is where ministerial accountability becomes a matter of epistemology, the theory of knowledge. The Ministerial Code, updated in January, says: “Ministers who knowingly mislead parliament will be expected to offer their resignation to the prime minister.”

She misled the select committee all right, but who can say she did so knowingly? “Should have known” is not the same thing. Her defence is incompetence, but philosophically it is watertight.

So May thinks Rudd lacks the iron grip of her predecessor at the Home Office, but Rudd is the prime minister’s crumple zone. If Rudd weren’t there to absorb the impact of anger over the Windrush scandal, the full force of it would be felt by the architect of the “hostile environment” policy, namely May herself.

That puts the home secretary in a paradoxically strong position. It helps to explain her unexpected answer at the press gallery lunch on Thursday, when she refused to rule out Britain staying in “a” customs union with the EU after Brexit. This was at odds with government policy, which is not to be part of any kind of customs union, and the Kremlinologists of Brexit were surprised when the “clarification”, in a tweet an hour later, said only that we will, “of course”, be leaving “the” customs union.

This seemed – and who can make a window into Rudd’s heart and say what she meant by it? – to be a deliberate pitch for the leadership of the “soft Brexit” faction of her party. Rudd knows, or should know, even if some of the articles about it may not have been in her red box, that Theresa May faces defeat on the question of a customs union.

I think May will compromise in the end, knowing that the hard Brexiteers probably don’t have the numbers to bring her down. But if we need an alternative prime minister who would take us out of the EU but keep us in a customs union, Rudd is, surprisingly, still available.