We may be living in the era of the email, but one young illustrator has proved that the art of correspondence is far from dead. While working for her degree at Glasgow School of Art Harriet Russell decided to find out exactly what lengths the men and women of the Royal Mail were willing to go to to ensure the safe delivery of her missives.

To put them to the test she concealed the addresses of 130 letters to herself in a series of increasingly complex puzzles and ciphers. Among the disguises she employed were dot-to-dot drawings, anagrams and cartoons. The answer, it seems, was very far indeed. Amazingly, only 10 failed to complete their journey back to her.

In another pleasing twist to the story, Ms Russell was unwittingly resurrecting a family tradition first begun by her great-great grandfather Henry Ponsonby, a private secretary to Queen Victoria and a veteran of the Crimean War. This eminent forebear embellished letters to his children at Eton with a series of illustrations in which he concealed the school's address. It was a family quirk continued by his son, Arthur Ponsonby, a pacifist who went on to be Labour MP for Sheffield Brightside before his elevation to the House of Lords.

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However, neither quite set about their task with the degree of invention employed by their 21st-century descendant who over the course of a year went to ever greater lengths to disguise her address.

These, it seemed gripped the imagination of Clydeside Royal Mail sorting workers as much as they did their author. Now the results of this unique and anonymous collaboration form the basis of a new book, Envelopes: A Puzzling Journey Through the Royal Mail, published by Allison & Busby, and hotly tipped as a stocking-filler hit this Christmas.

Ms Russell, 31, who now works from a studio in Wapping, east London, confesses that she had no idea her family had preceded her when it came to teasing the postman. She also admits she is no great letter writer, preferring to communicate by email: all the envelopes she sent contained nothing but blank sheets of paper.

She said: "It is an odd coincidence. We used to get a lot of wrongly addressed mail sent to our home, which was Shulbrede Priory in Surrey and that got me thinking about the postal system. The first one started as an experiment to see if it could get through."

Among the initial batch of envelopes was a letter with the address written in mirror writing. But it was not until sorting office staff forwarded one in which her street name and number were the answer to a series of crossword clues that she realised someone was taking their job very seriously indeed. Especially when the letter eventually flopped on to her mat with the boxes filled in and bearing the proud message: "Solved by the Glasgow Mail Centre."

She admits there were times when she worried that she might be in trouble for wasting Royal Mail time but still the letters continued to find their way back. "I was really quite amazed. I didn't know who was doing it. I imagined there was a small group of them and I think they must have caught on because a lot of them were to the same address." The identities of the sleuthing Royal Mail staff have never been established and Ms Russell, who also counts Hubert Parry, the composer of "Jerusalem" among her illustrious forebears, believes it is most likely they have moved on.

"I have never spoken to anyone and no one has come forward," she said. "But it is clear they were taking part and involving themselves in it."

The book, with its periodic tables, colour-blindness test and eye-chart addresses has already caused something of a stir in the United States although it is expected to do even better in the UK. The Bookseller has already described it as "a little treasure waiting to be discovered".

Ms Russell said: "I started out not knowing anything about my relatives doing this so my family dug out some of their old letters to show me."

For his part, Henry Ponsonby preferred whimsy to ciphers and cryptic clues. His letters bore addresses appearing as doodled signposts in snowstorms or as huge envelopes shouldered by tiny people.