HE named his rural idyll Little Sparta because of the struggle endured in making his artistic vision a reality.

Now those entrusted with Ian Hamilton Finlay's tranquil art garden have pledged to fight to save the haven from a recreational park expansion plan.

The cherished but fragile national art treasure that is home to a collection of 270 landscape poetry and sculpture works is so precious fewer than 5000 people are allowed to visit each year.

Supporters of the garden 25 miles from Edinburgh, at Dunsyre in South Lanarkshire, fear a new battle ahead with an MSP's push to widen the area's appeal and bring in more grant money to boost the local economy.

Little Sparta's guardians said they would mobilise to protect the aesthetic retreat as the park expansion plan was launched by Christine Grahame MSP to double the size of the Pentland Hills Regional Park.

The popular park currently draws about 500,000 visitors a year for activities including walking, cycling, horse riding, hill running and fishing.

The art garden tended by the Little Sparta Trust that took over the site following the artist's death in 2006 could be overwhelmed, Trust chairman Magnus Linklater warned.

He said: "Little Sparta is a peaceful and isolated place. It is not at all the kind of place we want huge numbers of visitors.

"What I think would undermine the whole integrity would be if there were streams of people walking past or a cross-country marathon or, heaven forbid, mountain bikers."

Ms Grahame, SNP MSP for Midlothian South, Tweeddale and Lauderdale, said she believed Little Sparta's identity could be preserved and also that its association with the park could help it bring in extra money.

She said: "We would look at ways of being able to protect what he [Hamilton Finlay] has done. I think it would fit in."

Mr Linklater said the trustees would not allow what he said is "one of the best kept secrets in Scotland" to be put in jeopardy and attracting more visitors was not a welcome prospect.

He said: "The garden is an immensely fragile place, cherished as one of Scotland's most important cultural treasures, and the Trust counts on the support of those who seek to extend the park in ensuring that its unique qualities are respected."

The garden was first established by Hamilton Finlay in 1966 and called Stoneypath.

It was renamed Little Sparta in 1983 by Hamilton Finlay, who died in 2006, in a sardonic tribute to his troubles with the establishment of Edinburgh - the Athens of the North - and separately with local government after a bitter tax wrangle.

His comparison played on the rivalry between the Ancient Greek city-states Athens and Sparta.

He clashed with the Scottish Arts Council when his work was withdrawn from an exhibition in Edinburgh and later was locked in battle with Strathclyde Regional Council after it tried to tax his Grand Temple as a barn.

That conflict is commemorated in the Monument to the First Battle of Little Sparta, the work that greets visitors.

The five-acre garden was voted "the most important work of Scottish art" in a survey of 50 Scottish artists and gallery professionals in 2004. The Pentland Hills Regional Park was set up in 1986 but takes in only 45% of the original 1970s planned area.

Ms Grahame believes ­ expansion will "enhance and promote the environmental and cultural assets while offering some protection against undesirable development". The consultation closes on May 23.