Sir Peter Paul Rubens' The Massacre of the Innocents smashed the record for the most expensive painting ever bought, or sold, in a British auction.

It had been was expected to sell for between �4m and �5m, but at the Sotheby's auction on Wednesday evening it went for a total of �49,506,650

Mr Gordon identified the painting as Rubens

The closing bid was �45m but a "buyer's premium" of �4.5m was added.

The new owner is an unnamed private collector so it is not known if the work will remain in the UK.

The purchase is the third most expensive for a painting at any auction in the world, subject to exchange rates at the time of sale.

The Rubens work was identified just weeks ago by Sotheby's expert George Gordon.

It was originally assumed to have been painted by Jan van den Hoecke, a follower of Rubens.

Greatest Rubens

"For such a work of genius by such a great painter to languish under a false attribution to a minor artist for so long is surely an injustice," said Mr Gordon.

"But in the end quality will out."

The Massacre of the Innocents was painted between 1609 and 1611.

Top Buys

$82.5m Portrait of Dr Gachet - Vincent Van Gogh, Christie's New York, 1990 $78.1m Au Moulin de la Galette - Auguste Renoir, Sotheby's New York, 1990 $76.7m The Massacre of the Innocents - Peter Paul Rubens, Sotheby's London, 2002 $71.5m Portrait de L'Artiste sans Barbe - Vincent Van Gogh, Christie's New York, 1998 $60.5m Still Life with Curtain, Pitcher, and Bowl of Fruit - Paul Cezanne, Sotheby's New York, 1999.

Sotheby's described it as "one of the most significant Old Master picture discoveries to be offered at auction for decades and the greatest Rubens to come to the market for more than 20 years".

More than 500 people crowded into the packed sale room and the bidding began at �3m.

A Sotheby's spokeswoman said: "It was completely wonderful. The bidding started at �3m, jumped to �3.2m, then �3.8m.

"Then somebody shouted out �6m and it went up in millions from then on.

"People were not messing around, they were very sure they wanted that painting."

She said there were four or five buyers who seemed determined to secure the work of art.

Unsold Rembrandt

The spokeswoman continued: "It was very exciting. Staff who have worked here for 30 years said they had never seen anything so wonderful."

The buyer was in the room and later emerged as Sam Fogg, a dealer who acquired the work on behalf of a private collector.

The Rembrandt was last sold 48 years ago

Rembrandt's Portrait of a Young Woman, painted in 1633, was expected to sell for between �10m and �15m, reached �8.8m in the bidding, but in the end went unsold.

It was the first time the painting had been seen in public for almost half a century, according to George Wachter, vice chairman of Sotheby's North and South America division.

"I have known and admired Rembrandt's Portrait of a Young Woman for almost 20 years," he said.

"The picture last changed hands 48 years ago and has not been seen on the open market since 1935."