Devolution explained — what is devolved and what is reserved

Scotland and Northern Ireland use a reserved-powers model: the legislature can legislate on anything except matters explicitly reserved to Westminster. Wales originally used a conferred-powers model — it could only legislate where power had been positively granted — and moved to the reserved-powers model in 2017, which substantially widened its competence.

Scotland's settlement is the broadest. It includes a separate legal system that predates devolution, income tax rate-setting powers on earned income under the Scotland Act 2016, and growing responsibility for social security benefits, delivered through Social Security Scotland.

Northern Ireland's arrangements are distinctive because they are underpinned by an international agreement. The 1998 Belfast (Good Friday) Agreement requires cross-community power-sharing, with a First Minister and deputy First Minister holding equal status and ministries allocated by party strength. If either designation withdraws, the institutions collapse — which has happened for extended periods.

Wales has expanded steadily, gaining primary legislative powers in 2011 and partial income tax rate-setting powers in 2019. It also legislates distinctively: Wales has led the UK on organ donation opt-out, on a 20 mph default speed limit and on a future generations duty on public bodies.

The division is not clean. Some subjects split awkwardly: employment law is reserved but public sector pay in devolved services is not; welfare is largely reserved but Scotland has significant devolved benefits; broadcasting is reserved but culture is not.

Where a devolved government wants to act on a reserved matter, it needs UK legislation or a transfer of power by order. This is a recurring source of friction, most visibly over the Scottish Government's attempts to legislate near the edge of its competence.

Devolved governments are funded mainly by a block grant from the UK Treasury, adjusted each year by the Barnett formula. The formula does not calculate need. It calculates change: when UK government spending on a comparable English service rises or falls, each devolved nation's grant is adjusted by a population-based share of that change.

Because it operates on changes rather than levels, historic differences in per-head spending persist. Spending per head remains higher in Scotland, Wales and Northern Ireland than in England, and the formula slowly narrows but does not eliminate the gap — an effect known as the Barnett squeeze.

The formula was devised in 1978 as a temporary administrative convenience by then Chief Secretary to the Treasury Joel Barnett, who later described its longevity as a mistake. It has no statutory basis and could be changed by the Treasury.

Where a nation raises its own tax — Scottish income tax being the main case — the block grant is reduced by a corresponding adjustment, so the devolved government bears the risk and reward of its own tax decisions.

England has no devolved legislature. Instead it has an evolving patchwork of combined authorities with directly elected mayors, covering areas including Greater Manchester, the West Midlands, West Yorkshire, Liverpool City Region, the North East and London. Powers are negotiated deal by deal and typically cover transport, adult skills, housing and some economic development.

This produces the West Lothian question, first posed in 1977: why should MPs representing Scottish, Welsh and Northern Irish seats vote on matters affecting only England, when English MPs cannot vote on the equivalent devolved matters? An attempted answer, English Votes for English Laws, operated from 2015 to 2021 before being abandoned as unworkable.

The Sewel convention states that the UK Parliament will not normally legislate on devolved matters without the consent of the relevant legislature. The Supreme Court confirmed in the 2017 Miller judgment that this is a political convention the courts will not enforce, which means devolved consent can be — and has been — overridden.

The settlement therefore remains genuinely unsettled. It has been revised by major legislation roughly every five to eight years since 1998, and there is no agreed endpoint.