The mainstream answer: it's the economy, not the constitution
Most economists explain Britain's decline without mentioning the Human Rights Act once. Productivity grew about 2.2% a year before 2008 and roughly 0.5% since, the "productivity puzzle." The NIESR estimates that if the old trend had held, output per worker would be about £5,000 higher today.
The cause they point to is investment. The UK has had close to the lowest investment in the G7 for almost every year since 1990, running around 3 points of GDP below the G7 average, still the lowest in the group in early 2026. Add the 2008 crash, Brexit uncertainty and weak demand, and you have a decline with no constitutional ingredient at all. If they are right, repealing the Human Rights Act fixes nothing.
The reply: the constitution sits upstream
Starkey's answer is that these are not rival explanations. The constitution sits above them. Britain often has the capital and the project and still cannot proceed, because it cannot give permission. Firms wait a decade for an electricity connection. Housing around Oxford and Cambridge is blocked. HS2 needed more than 8,000 separate consents. The binding constraint is frequently not money but a permission system in which unelected bodies and courts can halt almost anything and no minister can force the decision through.
Policy uncertainty, the very thing economists blame for low investment, is what a state looks like when it can no longer make a decision and make it stick.
On this reading the economic causes are real but downstream. A government that cannot build, cannot connect power, cannot deport and cannot hold a policy steady against legal challenge will under-invest and stagnate, whatever its tax rates. The constitution is the layer beneath the layer.
Honest verdict
This is a serious hypothesis, not a proof. The economic literature does not name the constitution as the main driver, and some of the decline (the 2008 crash, the global productivity slowdown, Brexit) clearly has non-constitutional causes. The strongest claim the evidence actually supports is narrower than Starkey's: the legal settlement is a real and underrated brake on the state's capacity to act, layered on top of economic problems it did not create. Whether it is the primary cause or one of several is not settled. Read the thesis as a case to test, not a verdict to accept.