LONDON (Reuters) - Sotheby's set a new auction record for Spanish artist Joan Miro on Tuesday when his 1927 painting "Peinture (Etoile Bleue)" fetched 23.6 million pounds ($36.9 million), but elsewhere the sale failed to meet expectations.

Overall, the auctioneer raised 75.0 million pounds ($117.7 million) at its impressionist and modern art evening sale in London, just beating the low estimate of 73 million pounds but falling short when buyer's premium is taken into account.

The auction was the first in a busy season of sales of fine art in London which, if the highest expectations are met, could raise up to $1 billion.

But it painted an uncertain picture, with the New York Times describing proceedings on the night as "lackluster" and "bumpy."

Confidence in the art market has been sky high in 2012 despite broader economic concerns, with emerging collectors from Russia, China and the Middle East helping push values to record highs as they seek to snap up the most coveted works.

On offer at Sotheby's was one of Miro's most important paintings, and the previous auction record for the artist of 16.8 million pounds was comfortably eclipsed.

"His works from this period are supremely modern, timeless and of great universal appeal, making this precisely the type of painting that today's international collectors are prepared to lock horns over, as they did this evening," said Helena Newman, head of Sotheby's impressionist and modern art in Europe.

The next highest price went to Pablo Picasso's "Homme Assis" which sold for 6.2 million pounds, again just above the low estimate but falling short after the buyer's premium is subtracted.

A Henry Moore sculpture, "Mother and Child With Apple", was one of the few star performers on a night when 15 of the 48 lots on offer went unsold. It raised 3.7 million pounds, well above pre-sale expectations of 1.8-2.8 million.

The London summer sales continue on Wednesday with the equivalent sale at Sotheby's rival Christie's. There, the 71 lots on offer are expected to raise between 86.5 and 126.7 million pounds.

(Reporting by Mike Collett-White, editing by Jill Serjeant and Todd Eastham)