Of all the daunting threats the Allies faced in the Second World War, German U-boats were among the most harmful. One young officer in the Women's Royal Naval Service (the Wrens) played a vital role in ending their reign of terror. Her name was Jean Laidlaw and after the war she would become not only an ICAEW Chartered Accountant, but a Fellow of the Institute.

The U-boat threat and wargames

In May and June 1940, U-boats claimed a total of 241 Allied ships, sinking 53 alone in the critical waters of the Atlantic. The key to that immense tally: so-called ‘Wolfpack’ ambushes. In such manoeuvres, groups of U-boats, each with a designated spotter vessel, would hunt for unsuspecting merchant convoys. By disrupting vital supply chains, the packs had the effect of making Winston Churchill fear for Britain’s starvation.

Convoy sinkings became a competitive sport between packs and for almost two years, the Allies were on the back foot. One major hindrance was that in 1935, admirals had told Royal Navy strategists not to factor U-boats into their big-table wargames. Plus, wargaming was stuck in a rut, used as a training exercise between wars, rather than a research and analysis tool while conflict was raging.

Some hope arrived in late 1941, when Commander Frederick John ‘Johnnie’ Walker devised the “Buttercup” tactic. When a convoy was attacked at night, its Navy escort ships would sweep to the flanks while launching extremely bright star shells to light up the waters. The escorts would then fire upon any enemy vessels caught in the light.

However, Buttercup was only sporadically effective. No one could predict the U-boats’ attacking pattern, nor pinpoint how they managed to sink so many ships while incurring so few losses.

Step right up, Jean Laidlaw.

A well-timed raspberry

In February 1942, aged just 21, Laidlaw became the first recruit to the Navy’s newly formed wargaming team the Western Approaches Tactical Unit (WATU), handpicked from the Wrens.

Overseeing appointments was Vera Laughton Matthews – a passionate feminist and former writer for The Suffragette who had served in the Wrens during the First World War, up to their disbandment in 1919. Twenty years later, the Wrens were revived, with Matthews as Director. While viewed by male Navy officers rather stereotypically as a pool of drivers and typists, Matthews’s Wrens were chosen based on their extraordinary accomplishments – their ranks crammed with athletes, mathematicians and other high achievers.

Alongside 65 other Wrens seconded to WATU’s Liverpool base, Laidlaw worked under Captain Gilbert Roberts – a naval wargaming guru brought out of retirement to crack the U-boats riddle. Roberts learned that the range of a U-boat torpedo was around one mile. As merchant convoys were typically spread out across several miles, that meant the Wolfpacks were sneaking inside their perimeters to attack ships at close range. Otherwise, they would not be able to pick off their prey with such uncanny precision.

So, what did that sneaking look like?

After rehearsing several wargame scenarios on WATU’s vast office floor, Laidlaw, Roberts and their team reasoned that the Wolfpacks’ element of surprise lay in their ability to move faster on the surface. So, at night, U-boats would steal in among convoy vessels on the waterline and torpedo ships astern. That done, they would plunge to maximum depth – far beyond the range of escorts’ hull-mounted sonar devices – wait for any remaining convoy vessels to pass overhead, then resurface behind them to slip away.

Armed with that tactical picture, Laidlaw hatched and christened the Allied response: Operation Raspberry. Under Raspberry, escorts would sweep a convoy’s entire perimeter during a German attack and assemble at the rear, considerably increasing opportunities to hit back at marauding packs and strike resurfaced U-boats.

Thinking differently unlocked advantages

Raspberry turned the tide. By the summer of 1942, U-boat losses had quadrupled. As a fighting force, the outwitted Wolfpacks were never the same again. By the end of the war, Laidlaw and her team of WATU Wrens had trained more than 5,000 Royal Navy officers through a host of wargames, leaving an indelible mark on Britain’s strategic prowess.

However, the same could not be said for Laidlaw’s own name. For the next few decades, she faded into obscurity – resurfacing in Sky History’s 2023 docu-drama U-Boat Wargamers, as played by actress Molly Vevers. Speaking to The Sunday Post ahead of the show’s first episode, Vevers described Laidlaw as “amazing” and said: “I think it’s important people know her story, and that she and the rest of the Wrens get the credit they deserve.”

As this year’s International Women’s Day urges employers to Accelerate Action for female equality, it is a story with enormous, present-day resonance. Particularly for what it tells us about the huge advantage that WATU gained by recruiting Laidlaw and other remarkable, young Wrens as a tactical brains trust.

Speaking to the Daily Mirror about the Sky series, historian Dr Tessa Dunlop suggested that the reason why the Wrens made such innovative breakthroughs in the collaborative atmosphere of WATU was because the Navy’s male-dominated, hierarchical structure could hinder lateral thought.

Although many of the Wrens were school-leavers, she noted, “they were telling men who had spent their whole lives at sea that they needed to think differently”.

Research that Vevers carried out to prepare for the part revealed a stark disparity: while Gilbert Roberts received a CBE for his work at WATU, none of the Wrens were formally recognised. It is believed, however, that he did take Laidlaw to Buckingham Palace when he accepted his CBE to share the honour with the team of remarkable young women that helped win the Battle of the Atlantic.

Peacetime and a new career

After leaving the WRNS as a First Officer, Laidlaw joined London accountancy firm Barber & Co and began studying to be an ICAEW Chartered Accountant at a time when less than 1% of the membership were women. She passed the Intermediate Examination in November 1948 and the Final Examination two years later.

Laidlaw was admitted to membership in 1951, one of just eight women that joined ICAEW that year. Even more remarkable, was that Laidlaw was immediately appointed as a Fellow of the Institute. This was something very unusual indeed and while there is no record of why this happened, there is speculation that it was in acknowledgment of her vital role in wartime.

As an FCA, Laidlaw continued to work with Barber & Co throughout the 1960s and 1970s, before moving on to Baker & Mckenzie at Aldwych House in the 1980s. Her final role was with Payne Hicks Beach in Lincolns Inn and Laidlaw became a life member of the ICAEW in 1996.

During her membership, women had gone from making up less than 1% of ICAEW Chartered Accountants to leading the Institute - ICAEW appoint its first female president, Dame Sheila Masters (now Baroness Noakes) in 1999.

As 2025 marks the 80th Anniversary of the end of the Second World War, a salute to the formidable achievements of Jean Laidlaw during the war and afterwards, is long overdue.