A Reluctant Home Front

In the spring of 1942, Ruth Jefferis felt increasingly like a war widow—though her husband was very much alive. After Mills Jefferis was assigned to Firs Hall, a clandestine weapons development facility, Ruth moved their three young children—John, David, and Jeremy—to a dilapidated cottage called Rose Cottage in the Buckinghamshire village of Cuddington. The rural setting should have been ideal for raising a family, but Mills was never home.

Their marriage showed early strains. Two years earlier, Mills had moved Ruth with a romantic gesture—filling their Mill Hill house with flowers—but such moments were rare. During a tense 60-kilometer drive through the countryside, Mills remained silent, his mind consumed by weapons designs. One explosive argument ended with Ruth storming out with a suitcase, only to relent when Mills chased her barefoot down the road. “It’s wartime,” she reminded herself. “He has important work to do.”

Determined to bridge the distance, Ruth took a job at Firs Hall itself, joining a team packing explosives into specialized bomb casings. She worked alongside “a dozen Welsh girls” recruited by Stuart Macrae, who oversaw production under Jefferis’ scientific direction.

The Improbable Weapons Factory

Firs Hall, an unassuming country estate near Whitchurch, had become Britain’s most secretive—and productive—weapons lab. Jefferis, a brilliant but eccentric engineer, led a team inventing devastating tools for sabotage:

– Limpet Mines: 15,000 produced in six months, shipped to commandos from Europe to Burma
– “L” Delay Switch: A revolutionary fuse with ±0.00001-inch precision in lead wire stretching
– Clam Mines: 10,000 units deployed against Nazi infrastructure

The workforce was as unconventional as the weapons. Among them:

– The Barber-Turned-Bombmaker: Mr. Brydall calmly packed explosives between haircuts
– The Flirtatious Welsh Girls: One repeatedly had to be extracted from a sentry box after hours
– The Playwright Carpenter: Gordon Norwood staged darkly comic plays like Woodchoppers’ Balls

Macrae maintained morale with a 35mm cinema, an illicit bar, and a monthly magazine—defying Jefferis’ puritanical “one Sunday off per month” rule.

The Mind Behind the Machines

Jefferis was a study in contradictions:

– Brilliance vs. Absentmindedness: He once solved a spring compression formula mid-bomb design, yet forgot days of the week
– Work Ethic vs. Distraction: Capable of 16-hour days but prone to mathematical tangents (like prime number theory)
– Innovation vs. Inflexibility: Created war-winning devices yet resisted staff entertainment

His crowning achievement—the “L” Switch—used Australian lead alloyed with tellurium for unprecedented timing precision. Even skeptical War Office officials admitted it was “a work of genius.” By war’s end, over 5 million units had been flawlessly deployed worldwide.

The Shadow Quartermaster

While Jefferis engineered, Major Colin Gubbins built Europe’s resistance networks. His Baker Street headquarters (officially SOE) became a guerrilla warfare nexus:

– Training: 667 Norwegians, 258 Poles, 209 Czechs, and others at Brickendonbury Manor
– Air Operations: Secured Halifax bombers and Lysander planes for agent insertions
– Radio Networks: 60+ wireless operators linked London to occupied territories

Gubbins fought bureaucratic battles as fiercely as the Nazis. When the RAF denied aircraft, he countered: “100 bombers may miss a target—one plane can deliver saboteurs who won’t.”

Legacy of the Secret War

The Firs Hall-Baker Street partnership changed warfare:

1. Precision Sabotage: Jefferis’ devices enabled pinpoint strikes without mass bombing
2. Resistance Warfare: Gubbins proved small teams could cripple Nazi logistics
3. Women in Combat Roles: Ruth and the Welsh girls pioneered female bomb technicians

Churchill recognized their impact, awarding Jefferis a CBE in 1942. Yet the true measure came in D-Day’s aftermath—when French rail lines (systematically severed by SOE teams) paralyzed German reinforcements.

As Macrae later wrote of the “L” Switch: “They were used worldwide without a single failure.” In the shadows of country estates and London townhouses, these unsung innovators had helped tilt the war’s balance.

The cottage at Cuddington still stands—a quiet testament to families who sacrificed normalcy so others might one day regain it.