Oscar-winning actress Emma Thompson and the Queen loved it but TV presenter Janet Street-Porter and journalist Lynn Truss were not so keen. They were all once in the Girl Guides and Brownies — the subject of a meticulously researched book by Oxford-based author Janie Hampton.

Despite the fact that her mother was a Brown Owl, Janie stuck the Guides for barely a year, dismissing it as “deeply uncool” while a teenager in the swinging sixties. So when she decided to write How the Girl Guides Won The War to mark the 100th anniversary of Girl Guiding, set up by Robert Baden-Powell in 1910, she approached the project with some scepticism.

She explained: “As a flower child of the 1960s, I am anti-uniform and anti-establishment so my initial thought was to do a satire but the more I researched, the more I realised what an amazing job they did. Girl Guides were also crucial to the development of feminism and women’s equality. Twenty years before women got the vote, Guides could earn badges for electrician, cycling, surveyor and telegraphist.”

Far from being elitist, she argues, Girl Guides was open to everyone from the start “regardless of class, creed or colour”.

Teenage parlour maids and factory workers were encouraged to join alongside the daughters of doctors, dukes and even kings. The Queen and Princess Margaret donned the uniform, albeit to attend a specially formed 1st Buckingham Palace Guide company in 1937.

At the other end of the spectrum, the 9th Oxfordshire Guide Company was run from the Savernake glove factory off Botley Road.

“I gradually realised that Baden-Powell was an egalitarian, a socialist and not racist. And he was right, there are times when discipline is essential,” said the author. Such as when a country is at war. Her book, as its title suggests, focuses on the role of the girls in uniform during the Second World War. Crammed with fascinating and occasionally mind-boggling anecdotes, it shows how Guides’ organisational and practical skills like first aid, fire lighting, cooking, sewing and knowledge of Morse code were suddenly invaluable. With thousands of evacuees, the transport system was in chaos. Guides patiently waited on railway platforms all over the country carrying luggage for tired mothers and looking after toddlers.

They dug shelters, carried messages, scrubbed houses being used for evacuees, knitted dishcloths and ran-up blackout blinds for the windows. “People who had never heard of Guides before realised how useful they could be,” she writes.

In Oxfordshire, the 1st Kennington collected jam jars, old batteries and newspapers before carting it four miles to the nearest scrap dealer. The 3rd North Oxford accumulated 4,000 books for the merchant navy and the 1st Kidlington handed out toys to sick children at the Radcliffe Infirmary and delivered mail.

Ms Hampton, who won acclaim for her previous book The Austerity Olympics, discovered one wartime Brownie pack was run inside a Japanese concentration camp, holding weekly meetings with their Brown Owl, who taught country dancing and took them through their badges. “That was the most amazing fact I unearthed in the archives. The entries read: ‘Today we sang our song…’ and it looked just like an ordinary log book at first sight,” she added.

From unpromising beginnings — Baden-Powell was not keen initially on the idea of female Scouts — within months of its launch, 60,000 girls all over Britain had enrolled. Apart from a sticky patch in the 1970s and 80s, it has continued to thrive and there are now ten million Guides and Brownies in 200 countries.

Although she didn’t spend long as a Guide, Ms Hampton was a Brownie for several years and believes this had more of a lasting impact. “I realised when writing this book that all my values come from being a Brownie. We were told to do a good deed every day and I still try to do that.”

As well as her work as a journalist and author, she is involved in a project with the Malawian government to turn a 19th-century steamer into a floating hospital.

“We are trying to raise £600,000, which sounds like an awful lot, but I think being a Brownie gave me the idea that anything is possible. That was one of Baden-Powell’s big things. Always strive a bit harder.”

l How the Girl Guides Won The War is published by Harper Press at £20.