Brexit a Failure? I think not!

You’re right that there’s an important counterargument missing. The usual answer to Brexit success,  reflects the mainstream economic interpretation, but many Brexit supporters argue that the UK has not actually implemented the kind of post-Brexit economic model they voted for.

A more balanced framing would include both perspectives.

Many pro-Brexit economists and politicians argue that Brexit itself did not inevitably make Britain higher-spending. Instead, they say successive UK governments failed to pursue the potential advantages of leaving the EU.

Their argument is roughly:

Brexit created policy freedom.
UK governments then chose continuity, caution, and higher spending rather than radical reform.

From that perspective, the issue is not “Brexit caused a bigger state,” but:

“Britain left the EU politically, while keeping much of the same economic model.”

Key arguments from that side include:

1. The UK did not seriously deregulate

Some Brexit advocates envisioned:

lighter regulation,
faster planning approval,
freer financial services,
simpler business rules,
more competitive tax policy.

But post-Brexit governments under Theresa May, Boris Johnson, and later governments largely maintained EU-derived regulations in many sectors.

Critics say Britain:

left EU institutions,
but kept much of the regulatory structure,
while adding new border bureaucracy on top.

So instead of becoming a low-regulation economy, the UK ended up with:

both domestic regulation
and trade frictions with Europe.
2. Governments increased spending for political reasons unrelated to Brexit

Brexit overlapped with:

COVID,
energy shocks,
aging demographics,
NHS pressures,
higher pension costs.

Brexit supporters argue that these would have increased spending even if the UK had remained in the EU.

They also point out that governments after 2019 adopted politically popular spending programs such as:

“levelling up,”
large infrastructure projects,
pandemic support,
energy subsidies.

Those were political choices, not direct requirements of Brexit.

3. Immigration did not fall in the way Brexit supporters expected

A major Brexit argument was replacing free movement with a controlled immigration system.

But after Brexit, net migration actually rose sharply for several years because governments expanded:

work visas,
student visas,
health and care visas.

Critics on the Brexit side argue this meant:

Britain incurred trade disruption costs,
while still maintaining high migration levels,
so the intended labour-market and wage effects never fully materialized.
4. The “Singapore-on-Thames” model was abandoned

Some Brexit advocates hoped for:

lower corporate taxes,
free ports,
aggressive global trade deals,
rapid innovation policy,
pro-growth reforms.

But after political instability and market turmoil during Liz Truss’s government, UK policy moved back toward fiscal caution.

Brexit supporters often argue:

“The UK never truly attempted the full pro-growth Brexit strategy.”

5. Brexit benefits are harder to measure than Brexit costs

Another argument is that:

trade barriers create immediate visible costs,
while sovereignty and policy flexibility create slower, indirect benefits.

Examples Brexit supporters cite include:

independent trade policy,
faster vaccine approval during COVID,
regulatory autonomy in areas like AI or finance,
ability to subsidize industries without EU state-aid rules,
fisheries and agricultural control.

Critics respond that many of these gains have so far been modest compared with the economic costs of weaker EU trade.

A more balanced conclusion

There are really two competing interpretations:

Mainstream economic view

Brexit reduced trade efficiency and investment, weakened growth, and therefore increased fiscal pressure and government spending.

Brexit-supporting view

Brexit created opportunities for a more competitive, lower-tax, deregulated economy, but UK governments largely failed to pursue those opportunities and instead expanded the state for separate political reasons.

So the disagreement is often less about whether Britain became higher-spending, and more about:

whether that outcome was an unavoidable consequence of Brexit,
or a result of post-Brexit political choices by successive governments.