The Scottish National Portrait Gallery has today unveiled a new acquisition, Portrait of Lady Montgomery by one of Scotland's greatest painters, Sir Henry Raeburn.

The full-length portrait was allocated to the SNPG through the Acceptance in Lieu of Tax scheme.

The galleries say it is a major work, by Raeburn, who lived from 1756-1823, the leading Scottish portrait painter of the late eighteenth and early nineteenth centuries.

Full-length portraits from Raeburn's late career are considered to be rare.

The painting presents a near life-size portrayal of Lady Helen Montgomery, nee Graham (d.1828), a wealthy Scottish heiress.

Lady Montgomery was the daughter of Thomas Graham of Kinross House, who had made, lost and re-made a fortune in India, before inheriting the family estates in Kinross and sitting as MP for Kinross-shire.

She married Sir James Montgomery, who achieved both local and national prominence as, first, an MP and, then, as Lord Advocate, in 1816. He erected Stobo Castle between 1805 and 1811. Lady Montgomery is notable for the considerable wealth and social standing she brought to her marriage, which resulted in the union of two well-established and influential Scottish families.

Christopher Baker director of the Scottish National Portrait Gallery, said: "This is a splendid addition to the Scottish National Portrait Gallery's collection.

"Raeburn had a remarkable ability to create an intimate and sensitive portrait within a grand format and here displays his slick technical skills with great mastery.

"We are very grateful to the Acceptance in Lieu scheme for making it possible for this impressive work to be transferred to public ownership.'

Probably commissioned to mark her then recent marriage in 1816, Raeburn's portrait presents Lady Montgomery in a simple dress that was highly fashionable at the time.

It is attached to the gold chain around her neck is a piece of jewellery which is probably a heart-shaped watch key, a possible reference to her new life.

The painting is presented in its original frame, which was made in Edinburgh in the early nineteenth century.

It was included as a key loan to the 1997 SNPG exhibition which explored and celebrated Raeburn's career.

In addition to the portrait of Lady Montgomery which is being unveiled today, the Scottish National Portrait Gallery has also been generously allocated through the Acceptance in Lieu scheme a portrayal, also by Raeburn, of her father-in-law, Sir James Montgomery. This work will be the focus of a later display at the Gallery.