As a former Treasury official, it’s always strange to see how much blame it gets for problem in Britain. Most arguments for breaking it up are very revealing. I have no issue with machinery of government changes which are designed to boost growth, though a wholesale move of economic policymaking to Manchester wouldn’t do that. But in most cases people who want to break up the Treasury aren’t doing it for growth, they just want it to stop controlling public spending. This would be a huge unforced error. The thing most people don’t know is happening behind the scenes: every other department in Whitehall is extremely profligate. The Treasury is the only organisation holding back a ballooning deficit from crashing our economy and hitting all our pay checks. My experience of working in a spending team was an endless torrent of calls for more spending, often badged as ‘investment’ but promising no return of any kind. Officials repeatedly lied, refused to admit what the real numbers were telling them, and hid spending from us at every turn. Ministers have every incentive to call for even more spending, and the issue of paying for it is always someone else’s problem - in this case, HMT, the Chief Secretary and the Chancellor. In the next few years we will need more broad fiscal consolidation - debt to GDP is unsustainable and as the last few days in the markets have shown, we are highly vulnerable to external shocks. Deliberately weakening the only bit of government which is prepared to manage that process, because of a misguided view that we can tax, borrow and spend our way to high growth and living standards, is usually the implicit motive, and sometimes the explicit one. Thankfully, it doesn’t seem like the PM wants to take control of spending and tax away from HMT. We’ll have to see which other economic levers this policy ends up covering. We all know the actual sources of growth - economic dynamism driven by low input costs like energy, cheap land and fast transport to work, and a permissive regulatory and tax environment which lets businesses make bets to grow and hire. I also think that done well, fiscal devolution and municipalisation could be good for the economy. These are all good candidates for No10 to take an assertive role in making policy. We should let the Treasury get on with the unenviable task for balancing the books. Nobody wants to be the one who tells the NHS or DWP they can’t spend more on vulnerable people, but often that is the case and someone has to make the trade offs. It’s other people’s money, and the taxpayer needs a strong seat at the table to protect their interests. Yes, it’s imperfect - often they don’t do a good enough job on supply-side reform, or they cut capital to permit more resource spending. But that’s partly because they’re faced with a bad set of choices forced by the rest of government, and have to make do as the only voice for growth at the table.