Paper Platoons: Why the SDR Has A Manpower Gap
The UK’s new defence strategy promises a modern force—but with troop numbers falling and no planned Army growth this Parliament, it’s a plan built on people who aren’t there.
Since the publication of the long-awaited Strategic Defence Review 2025 at the start of June, UK ministers have framed the moment as a turning point — an overdue rearmament in the face of war in Europe and escalating global instability.
As I wrote in my previous breakdown of the strategy, the SDR is a sprawling, forward looking document. It makes an ambitious pitch of a British armed forces that will transform into to a so-called “hybrid force” of digital and conventional strength, ready to fight and win in a new era of great-power rivalry.
Yet, at the heart of that transformation lies a basic prerequisite, personnel, and on that measure the armed forces are falling short.
A shrinking force
The headline numbers in the Ministry of Defence’s latest Quarterly Service Personnel Statistics, published on April 1, might suggest a modest decline but they mask a deeper problem. Between April 2024 and April 2025, the strength of the full time Armed Forces personnel, including Regulars, Reserves, and other categories, fell by around 3160 people. This equates to a 2% drop.
Some of these were replaced by personnel completing training. Nevertheless, this masks the fact that the deployable core of the military is shrinking significantly. Every service saw a drop in trained personnel: the Royal Navy and Royal Marines were down 2.8%, the Army down 2.3%, and the RAF down 2.5%. While small increases in support roles and Gurkhas helped soften the headline figure, these do nothing to reverse the hollowing out of the front line
In simple terms, the Armed Forces are losing trained personnel faster than they can recruit and train new ones.
The Reserve Forces aren’t faring any better. Between April 2024 and April 2025, the numbers of people leaving the volunteer reserve force numbers fell by 520 — a 1.6% drop. Within that, the Army Reserve fell by 1.5%, the RAF Reserve by 1.8%, and the Royal Naval Reserve by 2.1%. compared with the previous 12-month period. The idea that Reserves could help plug the gaps in national defence, a key pillar of the SDR — is already being undermined.
Pay rises – too little, too late?
The SDR does attempt to confront these challenges. It acknowledges, in unusually blunt terms, that the Ministry of Defence faces a recruitment and retention crisis. As a corrective, it promises the largest pay uplift for service personnel in two decades, backed by additional bonuses and financial incentives, particularly in hard-to-fill roles.
Over £1.5 billion has also been committed in this Parliament to improve accommodation standards, a long-overdue move after years of underinvestment in housing for forces families.
Yet while the pay rise and housing improvements will be welcome, they may not be enough. The data shows that the Armed Forces are continuing to lose trained personnel faster than they can recruit and retain them. In the year to April 2025, there were 11,160 new joiners across the Regular Forces. This figure that sounds solid until you compare it to the drop in trained personnel in that time. New joiners will need to be trained, and some of those won’t make the cut. Leavers continue to outpace entrants, and while flexible working schemes and financial incentives might slow the exodus, they are unlikely to reverse it.
The Armed Forces Pay Review Body, which backed the pay increase, acknowledged that monetary levers alone won't fix the problem. The same conclusion runs through the SDR itself: this is a workforce crisis with deep structural roots.
The cadet pipeline is a long game
Among the more visionary proposals in the SDR is a drive to rebuild the connection between society and defence through a major expansion of youth and part-time engagement. The government wants to grow the Cadet Forces by 30% by 2030, with the eventual goal of reaching 250,000 cadets — and to increase the number of Active Reserves by 20% in the 2030s.
The ambition is not misplaced. A broader base of public understanding and military literacy would be important to building national resilience, as is the case in some European countries. However, from a force readiness perspective, this is a slow-moving solution to a fast-moving problem.
A 30% increase in cadets is a decade-long project. Even if achieved, cadets today won’t enter the trained force in any meaningful numbers until the 2030s. It’s also highly unlikely that every single young cadet would go on to join the armed forces.
Likewise, growing the Reserves requires more than targets. It depends on recruitment infrastructure, consistent training pipelines, and credible incentives to attract mid-career professionals. The fact that Reserve numbers are already shrinking undercuts the idea that they can provide rapid capacity in the near term.
In short, the cadet and Reserve expansions are a sound idea but irrelevant to the immediate challenge of rebuilding the strength of the Armed Forces now.
No Army growth this parliament
In June, the Defence Secretary John Healey’s also confirmed that the size of the British Army will not increase during this Parliament. Despite all the talk of a revitalised defence posture and warfighting readiness, there will be no growth in the Army’s trained strength until after the next general election — likely beyond 2029.
This is more than just a scheduling problem. It undercuts the central narrative of the SDR that the UK is moving with urgency to rearm and reorient in a world where NATO readiness and deterrence are essential.
If the government accepts that the Army will not grow in the next four years, it is implicitly admitting that its short-term plans rest on a smaller, overstretched force.
A familiar fix: outsourcing recruitment
The MOD’s other major personnel initiative is administrative. In February 2025 new £1.5 billion recruitment contract was awarded to Serco, replacing the long-criticised Capita (often referred to as Crapita) contract. The move is intended to fix chronic bottlenecks in the recruitment system, blamed for missed targets and slow application processing times.
This change may amount to little more than reshuffling the deck. The Capita contract was also meant to revolutionise military recruitment. Without deeper reforms to how recruitment is marketed, processed, and supported — and without real cultural change inside the MOD, Serco contract will face the same issues. Moreover, in a labour market where cyber and tech skills are in high demand, the MOD is still competing with the private sector for the same digitally skilled workforce.
A strategy without staff
The Strategic Defence Review 2025 is filled with the right instincts: modernise, innovate, deter, grow. As I noted in my earlier analysis, it reads as both a geopolitical response to a more dangerous world and a genuine attempt to rebuild national defence capability. It fails to answer the simplest operational question of who will staff this force?
The statistics tell a clear story. Overall, the force is shrinking, not growing. Recruitment is lagging. Trained personnel are leaving faster than they’re replaced. The Army will not expand until at least 2029. The Reserves and cadet schemes are long-term plays. And while new contractors and better pay help at the margins, they don’t resolve the core gap between ambition and manpower.
This is not a strategy built on readiness. It is a strategy built on hopes for a force that does not yet exist.
Isn’t this at base a larger UK cultural issue. Simply that young people don’t see point/purpose of armed forces as currently defined. Whereas in Baltic countries young ppl doing National Service seem to see the Armed forces purpose is in defending their country’s culture and values against an all too present potential aggressor - Putin’s Russia.