This first week back in Parliament has proved quite how fragile the government’s power is. It may be able to govern in a technical sense – announcing bills, occupying Downing Street, and so on – but it cannot guarantee that it will get what it wants in the Commons.

Having to accept the Stella Creasy amendment on free abortions for women from Northern Ireland shows that, but this is just the start of a legislative free-for-all in which MPs from all parties are able to propose changes to any bill ministers put forward, and know that they stand an unusual chance of success. It just takes a handful of Tory MPs to sympathise with these changes, and then the government must either accept the amendment or face humiliation and defeat in a successful rebellion.

The deal with the DUP means the government knows it has support on its most important functions. But it also gives succour to those who want to argue for more funding for their own pet policy areas, or their local areas. Nigel Dodds’ defence of the deal at Prime Minister’s Questions on Wednesday was passionate and eloquent, but it was also incredibly helpful to MPs across the House who want to persuade the government to shell out more money for something. He told the Commons:

‘Suicide rates in Northern Ireland, particularly in my constituency, and issues of severe mental health are some of the worst in Europe, and indeed the developed world, and clinicians and others have pointed to the legacy of 30 years of terrorism and violence and the awful effects of that. Part of the money that we are investing this week will go to mental health care—extra investment in the health service. Is it not time that people recognised that this is delivery for all the people of Northern Ireland, across all sections of the community, and that it is going to help some of the most vulnerable and disadvantaged people in Northern Ireland? People should get behind it and welcome it.’

Focusing on the slice of money in the deal that will help treat mental health problems humanises it when the debate has become about ‘money for the DUP’ as opposed to money for the people of Northern Ireland. But it also enables an MP from, say, the North East, to argue that their region has the worst rates of cancer, or the lowest investment in infrastructure, and deserves more money, just as Northern Ireland deserved more money for mental health.

Add to this the sense that the electorate told politicians that they were, to quote Philip Hammond, ‘weary’ of austerity, and you have MPs pushing at an open door to coax more spending from ministers. This is good news for Parliament: it makes it incredibly powerful against the Executive. But it is very bad news for the Government, which will spend the next few months being held to ransom by any MP who is vaguely organised.