Sir David Wilkie, 'A Young Woman kneeling at a Prayer Desk', 1813

It is night-time and the tall Gothic windows of the chapel – perhaps in an aristocratic family home – are dark. A young girl kneels before an altar on which two tall candles in silver candlesticks have been lit. The air is still, for the flames burn steady and upright. Her hands are touched in prayer on a large open Bible, but we have interrupted her devotions and she turns to look at us.

Above the prayer table is a small altarpiece, but it is not possible to make out its subject. The inscription in a Gothic script above the image is the first part of the Lord’s Prayer: ‘Our Father who art in heaven hallowed be thy name thy kingdom come thy will be done.’

This portrait by the Scottish artist Sir David Wilkie is a small painting but remarkably rich in colour and deft in its painterly technique. The red velvet of the girl’s dress, the deep saturated colours and the scumbled brushwork of her white sleeves and collar are reminiscent of a Dutch old master painting. The portrait’s solemn manner is very different to the genre scenes in the style of the seventeenth-century Flemish painter Teniers for which Wilkie is better known.

The portrait is believed to be of Lady Augusta Phipps, the 12-year-old daughter of the 1st Earl Mulgrave. Wilkie captures with great accuracy and delicacy the face of a young girl poised between childhood and adulthood. The portrait has added poignancy because it was painted in 1813, the year Lady Augusta died. It may have been intended as a memorial to her.

Wilkie’s connection with the 1st Earl Mulgrave dates from 1806, when he and Sir George Beaumont visited Wilkie’s London lodgings and both commissioned paintings from him. Sir George Beaumont, who was instrumental in the foundation of the National Gallery, became the painter’s lifelong friend.

The portrait was recorded in an oil sketch – Display of Eight Paintings – that the artist sent to his brother, Captain Wilkie, who was an army officer in India. In 1872 it was put up for sale by a relative of the 1st Earl Mulgrave. It was then thought lost until it appeared in an auction in New York in 2014, where it was recognised by a London art dealer. It was purchased by the National Gallery thanks to a generous legacy from Marcia Lay, who had been an art teacher in a Birmingham girls‘ school. It is the second work by a Scottish painter to be acquired by the National Gallery; the first was ’The Archers' by Raeburn.