Some people are lucky with their relatives, including Oxford author Rebecca Gowers. One of her great-grandfathers, Douglas Pelly, provided the story to enable her to become a full-time writer. Now another great-grandfather, Ernest Gowers, has thrust her into the limelight again.

Ernest, who died in 1966 when she was a few months old, was the author of a famous post-war book on the art of good writing, based on three maxims — be short; be simple; and be human.

Plain Words, a bestseller for most of the 20th century, was written after he retired from a civil service career in which he had been responsible for the civil defence of London during the blitz.

One evening in 1943, he was asked to give an amusing talk to civil defence workers. With humorous regret, he poked fun at the government circulars that his audience received every week and called for a new style of official writing, both friendly and easy to understand.

The Treasury asked him to write a “training manual” for civil servants about using plain English. In 1948 Plain Words came out and sold 150,000 copies in eight months.

Before the war, Ernest had helped Lloyd George create the foundations of the welfare state, and after the war worked on the preservation of historic houses, but the success of Plain Words has eclipsed his distinguished public service career.

The Complete Plain Words, published in 1954, has never been out of print. To celebrate its 60th birthday, Rebecca has revised and updated the book for a new generation.

Despite her literary ancestors, her parents were both musicians. But she knew from the age of five that she wanted to be a writer.

After an English degree, she did what she describes as “low-level journalism” (which in fact included articles for the Guardian and Independent), then came to Oxford to do a doctorate in 19th-century detective literature.

While halfway through her research she was sidetracked by Pelly’s extraordinary life.

“It was a rather thrilling murder case. He was framed, in fact,” she said.

Pelly had emigrated to Canada in the early years of the 20th century Within a few days of arriving he found himself arrested on suspicion of murder.

When Rebecca looked into this story it became more mysterious the deeper she went. The published narratives of the four principal protagonists — the confidence trickster who was eventually tried and hanged for the murder, the detective, the Toronto Mail reporter and the author’s ancestor — contradicted one another to such an extent that clearly they were more than simply mendacious: they had been used as means to influence events to each writer’s benefit.

A publisher liked her idea for a book about the case, The Swamp of Death, and the advance enabled her to write full-time. She has been in Oxford ever since, combining writing with bringing up two children, now aged 13 and 15.

Her first published novel, When To Walk, featured abandoned wife Stella Ramble, a disabled travel writer whose journeys are from home to the library, trying to write a magazine article about ice sculptures while avoiding the words ‘frigid’ and ‘gelid’.

Then came Twisted Heart, about a contemporary Oxford student researching 19th-century literature, also in love with a library — in this case the Bodleian.

Rebecca made good use of her research career, highlighting the link between the murder of Nancy in Oliver Twist and the unsolved real life murder of a prostitute, Eliza Grimwood, in May 1832, channelling her beloved Dickens into a Gothic, macabre love story.

Plain Words seems completely different, but she says her books are linked by her almost obsessive interest in language.

“I find the subject fascinating, perhaps more than is right,” she said.

So was it daunting to follow in the footsteps of her illustrious ancestor?

“I came to the task as an ordinary person, rather than dispensing wisdom myself, from a mountain top. I tried to project myself as an ordinary reader, and I hope I have succeeded.”

Having spent several months of her life on the task, does she now find herself shuddering at people’s misuse of language, or the bad examples described in Plain Words?

“I would not dream of correcting people,” Rebecca said. “Other than my children. They get the full force of my obsession. But it would be most counter-productive just to randomly correct people.”

The Plain Words project was the result of “family feeling”, she says, that the previous edition (1986) was not only out of date, but had been edited in a way Ernest would not have approved of.

“It has a reputation in the family — we all understood that we didn’t like it. I did take a look at it and was almost upset. It had been rewritten by the previous editor in an opaque fashion, so that you can’t tell what is original and what has been messed about with.”

A homophobic diatribe about the changing use of the words ‘queer’ and ‘gay’ was among the passages she deleted from the 1986 version.

“There was no evidence that Ernest would have approved of that,” she explained.

Rebecca worked hard to restore more of the original Plain Words, and most of her additions and changes are clearly marked in notes. Her edition gives a striking picture of post-war Britain, with rationing and everyone pulling together in a truly universal age of austerity.

As well as references to coupons and requisitioning, German prisoners marrying local girls and the stop-me-and-buy-one ice-cream seller, there are ‘economic difficulties’, deficits and youth unemployment, and a debate on whether mothers should be ‘constrained’ to go out to work.

Rebecca’s aunt Ann Scott had written Ernest’s biography and Rebecca’s introduction draws on her research to explain how the book came to be written.

“She and my father and their cousins remember Ernest very well as a charming and delightful person. He has a very lovely reputation in the family “He was aged between 76 and 85 when he got going editing Fowler’s Dictionary of Modern English. He had been too busy before. He worked on it right up until the end, so he was a good advertisement for not stopping work.”

What strikes the modern reader, surrounded by diatribes from grammar pedants and the incredible popularity of books like Lynne Truss’s Eats, Shoots and Leaves, is how broad-minded this early 20th-century civil servant was.

“There are expectations that a book about how to write will be dogmatic, and possibly tending to be conservative.

“But he was clearly quite liberal for his time — and a democrat. He believed that how to write well was important, and part of human communication. The really important thing was to make yourself understood.

“The sense that you get from the book is born out by how he seems to have been in his private demeanour.”

She believes his campaign to make official documents more understandable has never been more important. “If you go on government websites and look at advisory documents, they are incredibly difficult to understand.

“Partly it is because the author is trying to make something straightforward seem more important — perhaps the whole thing has cost a lot of money.”

The chapters on grammar and punctuation are at the end of the book, preceded by (often hilarious) examples of obscured meaning, verbosity, unnecessarily impersonal language and jargon — and clear explanations of how this can be improved.

As she says in her preface: “Some believe that good English, bounded by antique superstitions, is their birthright, to be fought for with the ardour of the Light Brigade at Balaclava. Others dismiss so-called ‘good’ so-called ‘English’ as a risible manifestation of elitism. It is daunting to have to pick a path between these two camps, yet a fresh revision of Plain Words must do just that.”

Rebecca has evidently succeeded, because her publishers, Penguin, have asked her to write a follow-up.

She said: “It is a new book on language, with laughs. But they want me to keep quiet about it.”

* Plain Words by Ernest Gowers and Rebecca Gowers is published by Particular Books at £14.99.