Talk to any curator with his or her hands on the purse strings, and there will be the story of the one that got away:

Hepworths that proved too expensive, Rodins that went to America. For Mike Bailey, the first arts officer of Ayr's Maclaurin Collection, fresh in the job in the mid 1970s, it was a substantial Henry Moore sculpture. But somewhat unexpectedly, the Reclining Draped Figure which the tentative new purchasing committee of the Maclaurin Collection had rejected was subsequently bought by South Ayrshire Council, and now takes pride of place at Rozelle House. "After all that, we got a Henry Moore for free," smiles Bailey, who had been keen to make the purchase. Something of a lucky escape.

Notwithstanding the Moore, and given that it only started collecting art some 40 years ago, the Maclaurin has done rather well for itself. Now considered one of the best collections of 20th and 21st-century art in Scotland, and ranging from domestic to international works, the fruits of the Maclaurin's fossicking will go on display this winter in its near-entirety for the first time since the first work was acquired in the late 1970s.

Established in 1972, the Maclaurin was created from a substantial bequest from Mrs Mary Ellen Maclaurin, who wished to found an art gallery and collection in the name of her late husband.

Mrs Maclaurin gave the named trustees five years to fulfil the terms of her bequest, and the new art gallery was opened in the stable block at Rozelle House, Ayr, in 1976.

"We started the collection from scratch," explains Bailey, curator of this new exhibition. "I thought that it was more important to concentrate on having a varied and interesting exhibitions programme at first, but I found that in practice, as the collection developed, a symbiotic relationship developed. The more we collected, the better access we had to exciting exhibitions, including touring exhibitions from the Arts Council in London, for whom we were often the only Scottish show."

After the near miss with the Moore and a vast collection of American Abstract Expressionism from the collector Giuseppe Panza that eventually went to LA, the Maclaurin swiftly made its first purchases, an abstract by John Hoyland and a work by RB Kitaj. "The initial purchase took us two years, but in the following 12 months we bought another 12 works," says Bailey. "We exhibited the results in 1983 with a foreword by the then director of the National Gallery of Scotland, Colin Thompson. It was the diversity of that early collection that persuaded people that we should go ahead and develop it further."

The collection developed under Bailey's tenure, from Johns Bellany and Byrne via Bridget Riley, Roger Hilton and Terry Frost, and grew to over 30 works in the following couple of years. The collection now includes sculpture, painting and a substantial number of works on paper, and, after an early emphasis on collecting works from European artists outside Scotland, the Maclaurin now has an active policy of collecting Scottish artists.

"I think it's a well-rounded collection now," says Bailey. "Of course, there were things we didn't quite have the funds for, and we're a little low on German Expressionism, but I look back with great pleasure on those collecting years." And now the public can too.

The Maclaurin Festival is at the Maclaurin Gallery and Rozelle House in Ayr (01292 443708, www.themaclaurin.org.uk) from tomorrow until February 22