A devastated schoolteacher has lost four years’ worth of work on her second novel after brazen motorbike-riding thieves mounted a pavement and snatched her laptop in broad daylight.

Two thieves swooped on Le Pain Quotidien in Highgate’s high street on a stolen vehicle at about 6pm last week and took the £800 Macbook Air computer containing the only copy of Highgate School teacher Patricia Voute’s book.

The novel was to be based on her grandfather’s riches-to-rags life in Argentina, which years earlier she had promised her dying mother she would write.

The audacious crime follows a spate of mobile phone thefts by moped riders in nearby Crouch End and Highgate last month.

Ms Voute, who had been hoping to send a first draft of the book to her agent this week, said: “They did it so fast that my fingers were still typing. The shock of it. It was so brazen.

“The realisation that my work is all gone, that has been the horror,” said the religious studies teacher, of Shepherds Hill, Highgate.

“The book is still there in my head but the fine-tuning of each word, of each sentence: I can’t reconstruct that. I’ve lived in the Far East and in Argentina and I would never sit out with my laptop there, but this is Highgate.”

The first draft and years’ worth of research were stored on a distinctive memory stick with a blue suede leather foot-shaped keyring attached, which Ms Voute said she usually kept closely guarded.

But disastrously, the memory stick was plugged into the laptop at the time of the theft and taken by the muggers.

Ms Voute has no other copies.

The novel, titled Don Oscar, was to tell the extraordinary story of her grandfather, who left behind the disapproval of his wealthy colonial family in the late 1800s for a new life in Argentina, where he lived in a mud hut and married an impoverished villager.

Ms Voute had promised her mother she would retell his life story after she was diagnosed with a rare form of cancer and given three weeks to live by doctors years earlier.

Her mother defied all odds to survive, but Ms Voute remained determined to fulfil the promise and complete the novel.

But following the theft last Tuesday evening, Ms Voute said she will put the book on hiatus until she feels psychologically ready to rewrite the story.

She has low expectations of ever seeing her laptop again, but she has issued one final plea to the muggers.

“I would say to them, keep my laptop, but give me back my memory stick,” she said. No arrests have yet been made.

The area has seen a dramatic increase in moped and motorbike-related thefts since the start of the year.

Latest police figures show that there were three robberies and 10 thefts from a person in March in Highgate, compared with just three robberies and four thefts from a person in January and February.

In Crouch End, gangs from Camden and Islington were reported to be riding into Haringey to steal mobile phones from victims on the street.

Between January and March, there were 11 robberies and 13 thefts from a person in Crouch End.