On a windswept hillside midway between Wakefield, Huddersfield and Barnsley, Britain’s first and finest sculpture park is staging a spectacular birthday party. It’s forty years since Yorkshire Sculpture Park was founded, by a pioneering art teacher called Peter Murray. It’s since become one of the most influential artistic ventures in the country.

YSP’s 40th birthday bash is called A Weekend of Wonderful Things, and it’s a great way to discover the artworks in this immense outdoor arena. You can watch the sunrise in James Turrell’s Skyspace, go on a barefoot tour around the grounds, or enjoy a Caribbean Carnival amid Zak Ové’s arresting Anglo-Trinidadian statues. It’s a fitting anniversary for this innovative venue, which has transformed British attitudes to sculpture.

Ever since I was a student, I was very interested in the idea of making art accessible Peter Murray

Back in 1977 Murray was a lecturer here at Bretton Hall, a further education college with a strong emphasis on fine art. Before it became a college, in 1949, Bretton Hall was a stately home, and as well as the Georgian mansion at the centre of the estate, the college inherited its magnificent landscaped gardens.

“Ever since I was a student, I was very interested in the idea of making art accessible,” says Murray, over coffee in YSP’s sleek café. “I liked the idea of putting the arts in alternative spaces and places.”

In 1977 Murray had the bright idea of mounting a sculptural exhibition in these gardens. There were only a dozen exhibits, none of them by household names, but this modest show attracted huge interest.

Not everyone was keen. “There was a lot of public opposition,” recalls Peter. The local papers published angry letters from indignant members of the public, decrying these “metal girders and scrap iron” as “an insult to the intelligence of the taxpaying public.” However the vast majority of visitors were enthusiastic. They wanted to see more, and Yorkshire Sculpture Park was born.

Sculpture parks were already popular on the Continent (the Louisiana Museum of Modern Art in Denmark; the Kroller-Muller Museum in the Netherlands) but this had never been done before in Britain. For the UK, this was something new.