The engine room of government — and the room where government remembers how to be a government. Runs the civil service, elections, and the bits no other department wants to own.

The Cabinet Office sits at the centre of Whitehall. It supports the Prime Minister, coordinates policy across departments, oversees the Civil Service and is responsible for making the machinery of government function. It was created in December 1916, during the First World War, to bring order to a system that was not coping with the demands being placed upon it. More than a century later, the same description still applies. The department employs around 10,000 staff and is headquartered at 70 Whitehall. The Prime Minister is formally Minister for the Civil Service, while day to day political leadership sits with the Chancellor of the Duchy of Lancaster, currently Darren Jones, operating under the new title of Chief Secretary to the Prime Minister.
That coordinating role has itself been one of the least stable jobs in government. Since 2010 it has been held by Lord Strathclyde, Lord Hill of Oareford, Oliver Letwin, Sir Patrick McLoughlin, David Lidington, Michael Gove, Steve Barclay, Kit Malthouse, Nadhim Zahawi, Oliver Dowden and Pat McFadden before Jones. That is twelve holders in sixteen years. The office that exists to steady the rest of government has been subject to exactly the same churn that afflicts every department it is meant to coordinate.
The sharpest measure of the Cabinet Office's effectiveness is the Government Major Projects Portfolio. The whole life cost of the government's major projects stood at £442 billion, covering infrastructure, military capabilities, transformation, service delivery and information technology. In 2013 the then Infrastructure and Projects Authority judged 48 percent of those projects at least probable of successful delivery. By 2019 that figure had fallen to 17 percent. Fewer than one in five of the government's own major projects were considered likely to succeed, as judged by its own watchdog. The authority was dissolved in April 2025 and replaced by the National Infrastructure and Service Transformation Authority. New name, new acronym, the same underlying challenge. The UK had the lowest level of public investment in the G7 for 24 of the last 30 years, and the Cabinet Office sat at the centre of the system that produced that record.
Civil service reform tells a similar story of repeated ambition and limited traction. Departmental administration budgets are being cut by 11 percent in real terms between 2025/26 and 2028/29, with a further 5 percent in 2029/30 alone, and £150 million has been committed for civil service exit schemes. Successive governments have tried to shrink the civil service, and it invariably proves harder than ministers imagine. Headcount grew sharply during Covid and has been slow to fall back. The tension between demanding better delivery from departments and cutting the staff who deliver it has never been resolved, and the Cabinet Office has never found a way to make both objectives compatible.
There are reforms intended to break the pattern. All major projects in the portfolio must now publish a business case within four months of Treasury approval, a transparency measure designed to prevent the quiet inflation of costs that has characterised too many programmes. Whether transparency changes behaviour or simply produces better documented failure remains to be seen.
The department's role becomes most visible during national crises, and those crises have cut both ways. The Covid pandemic showed what the centre of government could do when circumstances demanded it, and what it could not. The vaccination programme was a genuine operational achievement. The VIP lane for protective equipment contracts, which gave politically connected suppliers faster access to public money, was a genuine failure of propriety. The Greensill affair, in which a former prime minister was granted extraordinary access to the Treasury on behalf of a financial firm that later collapsed, exposed weaknesses in the rules governing lobbying, conflicts of interest and the revolving door between government and private business. Both episodes pointed to the same structural problem. The Cabinet Office is responsible for the standards, ethics and coordination of government, yet was implicated in some of the most damaging breakdowns of those standards in modern memory.
A deeper criticism is that the department has increasingly become a political coordination unit for whichever prime minister occupies Downing Street, rather than the institutional engine for long term reform. Special advisers, communications strategy, policy units and political management have crowded out the slower, less glamorous work of improving procurement, workforce planning, digital capability and project delivery. Governments change. The structural problems remain, because they are never quite interesting enough to fix.
The Cabinet Office can point to genuine strengths. Britain retains stable institutions. Power transfers peacefully. The Civil Service is politically impartial and internationally respected. Government continues to function under enormous complexity. The new transparency rule and the creation of NISTA signal an intent to do better. These are real assets, and they should not be dismissed.
The larger question is whether functioning is enough. The public sees £442 billion of major projects with fewer than one in five judged likely to succeed. It sees administration budgets cut by 11 percent while the same departments are asked to deliver more. It sees lobbying scandals, procurement controversies and revolving door episodes originating from the very centre of government. It sees twelve holders of the coordinating role in sixteen years, none of them in post long enough to see a reform programme through. The department that exists to make government work has not yet made a convincing case that government works well enough. After a century of reviews, reform programmes, efficiency drives and reorganisations, Britain still struggles with the same administrative weaknesses that were identified decades ago. For the department at the centre of it all, that is the hardest verdict to answer.