Britain may never know when the next war has begun — and the government is scrambling to prepare for it.

A new classified “War Book” is being drawn up in Whitehall for the first time since 2004, as a leading defence expert warns that modern conflict could erupt without any of the visible warning signs that preceded previous wars — leaving the country dangerously unprepared.

“The modus operandi of the enemy, to engage in hybrid and cognitive warfare in advance of kinetic, means we may never enjoy a ‘last days of peace’ phase such as those activating the 1939 War Book did,” warns defence expert Paul Mason. “All 21st-century conflicts are cognitive.”

In plain English: the next war may already be under way before Britain realises it has started.

Chief of the Defence Staff Sir Richard Knighton has already confirmed Whitehall is writing a new War Book “in a modern context, with modern society and modern infrastructure.”

The development follows Sir Keir Starmer forming a Middle East Response Committee to handle the escalating US-Iran confrontation.

Who is raising the alarm?

Mason, an honorary senior fellow at the University of Exeter, has urged ministers to rebuild the War Book framework and place it under explicit democratic control — insisting any emergency powers it contains must be “just and reversible” rather than a blank cheque for the state, reports the International Business Times.

Mason argues the removal of the old War Book twenty years ago has created a “vacuum of public assumptions about what the state might do if the UK found itself on the brink of kinetic war.”

While the Middle East Response Committee is focused on a specific regional flashpoint, Mason’s briefing widens the lens considerably — asking whether Britain is structurally ready for any serious clash with a peer adversary.

Why might there be no warning before conflict?

Mason’s most striking argument is that the idea of a clearly signposted run-up to war — the kind of visible, tense countdown that preceded 1939 — no longer applies.

The original War Book underpinned government planning from 1939 onwards, providing a detailed roadmap for how departments would mobilise the economy, control information and protect critical infrastructure — before being quietly scrapped in 2004.

Without it, the country has been left without a shared framework for understanding what a slide towards conflict would actually look like.

In other words, information, perception and morale are already battlefields long before a single shot is fired.

What does Mason want the War Book to include?

Mason’s central concern is not just military hardware but public consent. “If the population does not support the state in wartime, and conform to the behaviours required, the war could be lost strategically even if it could be won operationally,” he argues.

Rather than cajoling a population into an emergency footing on the fly, Mason’s logic is that citizens, businesses and institutions need to know in advance what might be asked of them, who is in charge and where the limits of state power lie. Without that preparation, he warns, “the more the state risks ‘flying blind’ in any situation where peer-vs-peer war becomes likely.”

What structural changes does a wartime UK need?

Mason’s briefing proposes a dramatic restructuring of government in the event of conflict. He recommends reshaping Whitehall “around the overriding aim, to win by maintaining the will and the means to fight for longer than the adversary” — including a “Ministry of War Production, with powers to command and control the private sector” and a dedicated “Ministry of Economic Warfare” to handle economic security functions.

These are not minor adjustments but a suggestion that the state would assume far more direct control over industry and finance in wartime.

On information, Mason calls for a “modernised wartime public information duty” for the BBC, effectively reviving its historic role as a trusted national communicator during crises. He also recommends a “Lithuanian-style hardened secure state communications system” to protect government messaging from hostile interference.

What has the government said about the War Book?

The government has confirmed only that a new War Book is in development. The precise powers, structures and institutional changes remain unannounced, and no public draft of the forthcoming Defence Readiness Bill has been published.

Mason is unequivocal about the stakes. “Achieving maximum clarity and transparency at the design stage will be crucial for whole-of-society acceptance that such emergency provision exists, even if it is never activated,” he concludes.