The Army relies on reservists who also have day jobs. The problems their absence create for their employers are offset by the range of skills the employees bring back. Peter Crush reports.

Bombs are not selective about whom they injure; they will detonate and destroy anyone who disturbs them, regardless of whether the Royal Engineers searching for them are alert and hydrated, or 59 minutes into a one-hour reconnoitre.

This frightening fact is a daily reality for the 'sappers' (soldiers) of 101 (City of London) Engineer Regiment - EOD (Volunteer) squadron. For six months they have swapped the safety of Catford in south-east London for temperatures of 42 degrees in sun-baked Cyprus. Their job is to find and make safe the unexploded bullets, missiles, grenades and shells that still litter the ground in areas of this disputed country more than 30 years after Turkey and Greece took up arms against each other. As I watch them painstakingly surveying one square-metre grids that stretch far into the distance, it is sobering to discover that all of these men and women risking their lives, doing regular Army jobs, are volunteers, and all of them have civilian careers.

The work I am witnessing is the extreme end of volunteering. The Armed Forces is currently suffering from a 5,000-person deficit, and is increasingly relying on its volunteer base - those in the Territorial Army (TA) and the Navy, Air Force and Royal Marines reserves. Some 39,000 workers (and a further 174,000 ex-regulars who can still be called up) are reservists in their spare time. Most of the time their hobby has little impact on their day jobs. They must complete a minimum of 35 days' training per year - including a two-week camp that many of them take as part of their annual holiday entitlement. However, on average, once every three years, reservists are called up for a mandatory six-month tour of duty. Businesses cannot normally object. In theory it means any employer with reservists on its payroll might have a member of staff absent for one year out of a 3.5-year block of time.

Such is the impact reservists have on employers, but so vital are they to the Armed Forces, (101 Regiment is 54% volunteer) that an MoD agency - SaBRE - exists simply to smooth over the cracks that could appear. Without the goodwill of employers, the Army would simply not be able to operate. TA numbers (at 34,117) have already hit a 100-year low and, according to commander Terence Smith who travelled with me, turnover in TA personnel is 20%-25% per year. Key to the TA's retention levels is employers giving their reservist staff the support they need. At the same time SaBRE is acutely aware a dedicated TA volunteer can cause severe business continuity problems.

"The NHS and BT are among the largest employers of reservists," says Captain Tim Hebberd, MoD escort officer. "There is compulsory mobilisation for skills in short supply and very few employers have won exemption. Our job is to explain the benefits reservists can bring back to organisations."

A report by John Moores, Leeds and Bradford universities found that routine TA tactics courses - equivalent to level 4 and 5 management training - would cost up £4,200 to buy on the open market, and develop heightened teamwork, self-confidence and leadership skills. I spoke to just some of the TA reservists out there who manage to combine a career with Army duties.

RACHEL MAHONY, (27) SURFACE SCANNING

Mahony had spent two days prior to my arrival clearing surface material from a former grenade and anti-tank range. She is responsible for guaranteeing her area is 100% metal-free to a depth of 200 millimetres. She says: "I'm an ex-cadet, I first started this in 1999. My volunteering pre-dates the start of my career, and this is my second tour of duty. I now work as a barrister at the Crown Prosecution Service. Work has largely been supportive - I spend 87 days a year volunteering, not including this tour. They know I bring back skills. Thanks to the TA, at my age I feel I can relate to clients better when I'm in court."

SERGEANT RICHARD MAY, (49) EXPLOSIVES CLEARANCE

"I'm a project manager, stations development at Network Rail, where I've worked for 20 years. I've never considered working for the Army full time, but I've been a TA reservist for the past 20 years. I've had several mobilisations, one of which was for an entire year. People have moaned about me being away from work, and shift working is difficult to cover. Some of my colleagues have to take over my workload, but overall HR is very supportive. It realises what I can bring back to the business. Luckily quite a few TAs work at Network Rail - a colleague is a sergeant major. Being a TA is good for retention. I've been with Network Rail for the past 20 years because I feel refreshed when I return from Army duties."

DAVID GREEN, (51) ROYAL SIGNALS

You may recognise this face. Green is an actor, and has already been shot at and killed playing 008 alongside Pierce Brosnan in the James Bond films. "I'm very much alive in this job," he says. "At 51 I'm nearing the end of my career as a TA, but being an actor makes it easier for me than for most. I would expect to fit it into the day job. I do more than 100 days per year in the TA, and have fought in Northern Ireland and Iraq."