Experts restoring a painting by one of Australia's best-known artists, Arthur Streeton, have stumbled across a 120-year-old love story concealed in the canvas. The impressionist work,Spring, which was completed in 1890, depicts an idyllic rural Australian scene, with a group of naked boys bathing in a hillside stream.

But when Michael Varcoe-Cocks, a conservator with the National Gallery of Victoria, examined it under a microscope, he discovered the words "Florry Walker's my sweetheart", inscribed several times. The gallery then X-rayed the work and found a nude female figure, which had been painted over.

Mr Varcoe-Cocks spent more than a year restoring Spring, which acquired 14 bullet holes while hanging in an Australian mansion at the turn of the 20th century. The gentleman of the house had invited some friends for dinner and, after a few drinks, they got their rifles and took potshots at the cows lazing in the background.

The declarations of love, invisible to the naked eye, were inscribed using a fine point when the paint was still wet. The discovery intrigued gallery staff, who set off to establish the identity of the object of Streeton's romantic attention.

Mr Varcoe-Cocks knew Streeton had been to art school with a painter called Lucy Walker. Searching through birth and death records, he discovered she had a younger sister called Florence. Last week, the gallery contacted Florence's descendants, who confirmed there had been a brief romance, which was part of family folklore.

The family also had a previously unknown work that Streeton - a leading member of Australia's first art movement, the Heidelberg school - had given to Florence. The painting, A Flight of Summer, which has been loaned to the gallery and was unveiled yesterday, shows a mysterious female figure wreathed in smoke.

Streeton, who was heavily influenced by the French Impressionists, was 24 when he painted Spring. He was living in Melbourne at the time. His grandson, Oliver Streeton, told Australian Associated Press yesterday that A Flight of Summer appeared to reveal a painful end to the love story. "Look at the thorns," he said, referring to rosehips in the painting.

"Maybe this was his first great disappointment. I fancy Arthur Streeton has realised there's no hope with Florry, that's my guess. Her family were reasonably well off, but Arthur Streeton, of course, being an artist, was fairly low in the food chain. I can only surmise his prospects with Florry weren't very great."

Florence married someone else, as did Streeton, although in his case not until he was 41. Letters that he wrote to Florence have been lost. Mr Varcoe-Cocks removed a discoloured coating from Spring, apparently applied in an attempt to patch the bullet holes. "It's the process [of restoration] that's revealed this story," he said.

He said the secret messages - which include "Florrie and Smike (Streeton's nickname)" - were like words "written in wet pavement... or wet cement".