As Andy Burnham prepares to take over as Prime Minister, we still have no idea who will be the next Home Secretary. It might even still be Shabana Mahmood, if the new PM decides to make someone else Chancellor.

But whoever it is, there’s a strong case that Mahmood is the first Home Secretary since Theresa May in 2016 to leave the job with their reputation enhanced. Mahmood had an important job before, as Justice Secretary but if you’d asked 100 people in the street to identify her, I doubt if more than 99 would have been able to. The role of Home Secretary is far more high profile; one can confidently assert that at least 98 would be able to name her now.

Any significant watering down will show that Burnham is going to return Labour to its comfort zone

In other words, it’s not so much who she is as what she has done as Home Secretary that matters. And what she has done is to introduce a comprehensive set of reforms that tackle one of the most toxic issues in politics: immigration. Specifically, under the Immigration and Asylum Bill introduced just last month, the notion of “family life” as set out in Article 8 of the European Convention on Human Rights is narrowed to immediate family; foreign criminals with serious convictions lose their protected status; a new appeals authority to replace the First-tier Tribunal is introduced; and asylum seekers in public accommodation are required to contribute to their upkeep once able. All these changes are designed to lead to fewer arrivals, more removals and controlled safe routes.

The bill follows rule changes introduced in March in which refugee protection was cut from five years to 30 months, renewable only where there is continuing need, with return expected once a home country is deemed safe; a default 20-year qualifying period for permanent settlement; and the previous statutory duty to support asylum seekers replaced with conditional support, withdrawn from those who break the law or can support themselves.

The argument for Mahmood’s reforms is not only based on the intrinsic merit of a more streamlined, clearer and fairer system. One man’s fairness is, after all, another woman’s “unfair” and “Un-British” (as the former Deputy PM Angela Rayner called Mahmood’s changes). Not only one woman, in fact: nearly 80 Labour MPs wrote to Andy Burnham earlier this month demanding that he kill off the plan to apply stricter settlement rules to migrants already here. They called the changes “anathema to who we are, what we stand for and how we should do politics”.

It’s reported today that the same Labour MPs – and possibly more – want to take the opportunity of a new Home Secretary to destroy the reforms. It’s said they want Burnham to “review and refresh” Mahmood’s plans – specifically the doubling of the time needed to qualify for indefinite leave to remain (ILR), which grants foreign nationals the right to live, work, study and claim benefits in the UK permanently.

Mahmood announced that this would apply to 1.6 million migrants who have arrived since 2021 under the “Boris-wave”. One Labour MP is quoted as saying of Mahmood’s possible departure from the Home Office: “Hopefully that will mean we’ll be re-examining the proposals so it’s a chance for a review and a refresh.”

Various ideas have been floated, such as exempting 600,000 foreign care workers and their families from the need to wait longer for ILR, and allowing all current migrants to gain ILR under the existing five-year timetable but restricting their access to benefits for another three or four years.

There is, however, a further, deeper basis to Mahmood’s reforms – or rather to the need for Burnham to keep them, whoever becomes Home Secretary. They are a touchstone – and an immediate guide – for his time as PM. Any significant watering down will show that Burnham is going to return Labour to its comfort zone, with policy focused on the ideological knee jerks of Labour MPs and Labour supporters.

As it is, Burnham has already flip-flopped on the reforms, having attacked them before returning as an MP because they leave people “in a sense of limbo and unable to integrate” – then saying that he supported them mid-campaign in Makerfield. Capitulation over the reforms would be a clear statement of who actually runs his government. If his first act is to let Labour MPs gut the immigration reforms, every future fight – spending, tax, foreign policy – would set the precedent that pressure works.

It’s not as if the broader political importance of immigration reform is obscure: one of the strongest factors behind the Conservative defeat in 2024 was the view that it had lost control, made all the worse by its promise to restore control.

Reform, which for all Nigel Farage’s current travails still leads the polls, feeds off broken promises and Burnham could be holed below the waterline from the start if he unravels one of the key policies designed to show that Labour understands the pressing concern of voters over immigration and asylum. In 2022, for example, the public was by 34 points more likely to say immigration was good for the economy; by early 2026, the balance was negative.

Weakening Mahmood’s reforms would gift-wrap Reform what seems still likely to be one of the key issues of the next election. Is that really the start Burnham wants?