David Hockney’s first English landscape to be shown for the first time in nearly 30 years | David Hockney

David Hockney’s first English landscape, which depicts a perfectly manicured Oxfordshire garden, is on display for the first time in three decades before being sold at auction.

Sotheby’s said the 1965 painting The English Garden, completed in Boulder, Colorado, was pivotal for Hockney, as well as holding an important place in broader art history.

“It’s a moving painting,” said Tom Edison, co-head of contemporary art at Sotheby’s in London. “It really lays the foundations for everything that comes next.”

The painting was displayed in the auction house’s central London galleries before being sold on March 4, with an estimated price of between £2.5 million and £3.5 million.

He had not been out of the Hockney School of Art long when he moved to the United States, and in the summer of 1965 he was invited to teach at the University of Boulder, Colorado.

He found himself a lover, a 19-year-old student named Dale Cheesman, who enjoyed his six weeks in Boulder, but was given a studio without windows.

“Here I am surrounded by these beautiful, rocky mountains,” he told his biographer. “I go into the studio – no window! All I need are a few little windows.”

Searching for inspiration, he came across an American Vogue photo taken by Horst P. Horst of a sculptural topiary garden in Hasley Court, Oxfordshire, home of designer and tastemaker Nancy Lancaster.

Edison said: “You get a feeling of nostalgia, and perhaps a little homesickness, when you look out upon the green and pleasant lands of England… I think this prompted him to paint his homeland.”

The English Garden is Hockney’s first fully realized English landscape and was painted at a time when abstract, not figurative, art was the dominant force.

Edison said the work was particularly exciting “because it reinforces so much of what we know about Hockney’s practice and what we all love about him as an artist… It was a real turning point.”

Edison said that outside his California swimming pool paintings, Bradford-born Hockney’s latest paintings of East Yorkshire landscapes are among the best-known and most popular paintings of his career.

He added that the direct link can be seen in the English Garden.

The painting was exhibited at the Kasmin Gallery in London in the year it was painted and was last shown in a public exhibition at a 1970 exhibition at the Whitechapel Gallery in London. It has been in private hands ever since, appearing at auction in 1997.

Hockney, now 88, remains busy with an exhibition of his new works that will open at the Serpentine Gallery in London in March.

It follows Hockey’s largest-ever show last year, when more than 400 of his works were displayed at the Fondation Louis Vuitton in Paris, where Edison said visitors could see the scale of the artist’s ambition and “extraordinary” motivations.

“He is constantly challenging himself. He continues to be at the forefront of contemporary art and this painting [English Garden] For me, he is the origin of everything that came after him.