A PAINTING that hung on the walls of the National Galleries of Scotland for thirty years is to be sold at auction for up to £20m.

The masterpiece by one of Britain's greatest painters, JMW Turner, entitled 'Rome, from Mount Aventine' has been on loan to the NGS since 1978.

Now the oil painting, from 1835, is to be sold at the Sotheby's sale of Old Masters in December, and is estimated to reach from £15m to £20m.

It was acquired by the 5th Earl of Rosebery in 1878 and has been in the private Rosebery Collection ever since, although loaned to the NGS.

However earlier this year it was removed from the galleries, where it has been one of the highlights of the national collection and shown on the main floor of the National Gallery, in preparation for the sale later this year. It was part of the last major Turner show at the NGS, Turner and Italy, which ran in 2009 at the Royal Scottish Academy Building.

The NGS declined to comment on the sale of the painting last night, and would not comment on whether it would be making a bid for the painting in December - although if it did, it would need substantial aid from other public sources of funds, including the Government and Lottery funds.

Views of Rome obsessed Turner (1775-1851) for two decades.