Canaletto painting, once owned by first British prime minister, heads to auction

LONDON (Reuters) -A painting by Italian artist Giovanni Antonio Canal, best known as Canaletto, which was once owned by Britain's first prime minister, heads to auction next month, with a price estimate of more than $27 million.

"Venice, the Return of the Bucintoro on Ascension Day", from around 1732, has only been offered for auction twice before and will lead the July 1 "Old Masters Evening Sale" during Christie’s Classic Week in London.

It is listed with an "estimate on request, in excess of 20 million pounds" ($27.09 million) price tag.

The painting depicts the Bucintoro, the official barge of the Doge of Venice, returning to the quay side on the feast of the Ascension.

"It's a ten out of ten on every measure... This is the grandest view you could possibly conceive of Venice at its grandest moment, Ascension Day, with all of the pomp and ceremony," Andrew Fletcher, Christie's global head of the Old Masters Department, told Reuters.

"It's in unbelievably beautiful condition, partly because it's passed through so few collections over its lifetime."

The painting looks towards the entrance of Venice's Grand Canal as the Bucintoro returns to the Doge's Palace.

"Perhaps the most extraordinary thing about this painting is that it is possibly the picture which set off the craze for works by Canaletto in the United Kingdom, which of course was the country and the people who were his greatest patrons," Fletcher said.

It once hung at 10 Downing Street, the official residence of British prime ministers. It was first recorded there in 1736, in the collection of Sir Robert Walpole, generally regarded as Britain's first prime minister.

It was sold at auction after his death and bought by the financier Samson Gideon. It remained in Gideon's family until 1930 and last came to auction in 1993.

"It is painted in the early 1730s, which is generally considered the apex... of Canaletto’s output," Fletcher said.

"This is the time where he had left behind the sort of ultra atmospheric views of the 1720s, had found this formula on which his fame would then ride - this sort of very detailed but actually quite limited palette, but focusing very much on the detail of, and the beauty of, the Venetian architecture and people."

($1 = 0.7382 pounds)

(Reporting by Marie-Louise GumuchianEditing by Gareth Jones)