Thousands of former British military personnel could be called up as part of a major government exercise next year, designed to test how well the UK could respond if conflict broke out.
What the exercise will involve
The drill, planned for 2027, will challenge the Ministry of Defence (MoD) “on a scale that we haven’t seen for a very long time,” according to armed forces minister Louise Sandher-Jones. It will draw on Britain’s strategic reserve — a pool of an estimated 95,000 retired regular and reserve officers who can, in theory, be called back into service. The exact number involved hasn’t yet been confirmed.
The exercise will test the practical steps needed to mobilise this reserve at scale, from calling people up to equipping them, should the need ever arise.
Why the MoD wants a “step change”
The plan forms part of a wider push by the MoD to make far greater use of its strategic reserve, following warnings of a crisis in retaining military personnel. Air Chief Marshal Sir Richard Knighton, the chief of the defence staff, warned in January that there wasn’t an effective system in place for keeping in touch with reservists.
Sandher-Jones, who served as an intelligence officer in the Army before becoming an MP, is herself part of the strategic reserve. She admitted that when she left the Army, she barely gave her reservist status a second thought. “Certainly when I left the Army and found out I was in the strategic reserve, I just filed it away and never thought about it again,” she told the House of Lords national resilience committee. “We are definitely no longer in that space — the strategic reserve is a real commitment for those who are in it, and they will be exercised as part of our exercise programme next year.”
Earlier this year, the government raised the upper age limit for the strategic reserve, which spans the Army, Navy and RAF, from 55 to 65, and made it easier to call reservists into service.
Part of a bigger resilience push
The announcement comes as the government faces pressure to raise defence spending to 3% of GDP by the end of the decade, up from around 2.4% last year, according to NATO figures. Ministers are also preparing a public awareness campaign encouraging people to prepare for emergencies, which reports suggest could include advice on stockpiling tinned food and bottled water in case of extreme weather or cyber attacks. Sandher-Jones pointed to Finland as a model, praising its recent civil defence exercise — Europe’s largest since the Second World War — which saw more than 2,000 people take part.
Bringing young people into the fold
Sandher-Jones said young people would be essential to future readiness. She suggested the military’s new “gap year” scheme for under-25s, which began recruiting its first 150 students in December, could be expanded quickly if it proves successful. She also said the military could help tackle the number of young people classed as NEET (not in education, employment or training) — currently one in eight in the UK — by expanding cadet programmes in schools.
Understanding the strategic reserve
The strategic reserve differs from the regular Army Reserve in that it’s made up of former full-time personnel who have already left service, rather than part-time volunteers — meaning many reservists may not have trained or served for years before being asked to step forward again.
Learning from Finland
Finland’s civil defence system is often held up as a benchmark in Europe. The country maintains around 50,500 civil defence shelters with space for roughly 4.8 million people — close to Finland’s entire population of about 5.6 million — with coverage concentrated in cities, where shelters are built into apartment blocks, schools and car parks. This kind of nationwide preparedness, built up over decades, is part of what Sandher-Jones and other ministers have pointed to as an example the UK could learn from as it strengthens its own resilience planning.
