Anthony van Dyck, 'Lord John Stuart and his Brother, Lord Bernard Stuart', about 1638

This imposing, life-size double portrait shows the youngest of the seven sons of the 3rd Duke of Lennox: Lord John Stuart, on the left, with his brother Lord Bernard Stuart, later Earl of Lichfield. The two young men – they were probably aged 17 and 18 at the time – ooze aristocratic superiority. There is nothing natural or spontaneous about their poses; they are instead the embodiment of affectation.

One brother, leaning nonchalantly on a stone parapet, does not even deign to notice us. The other glances down over his shoulder, lifting his cloak to reveal its fabulous silver lining and to emphasise the tip of his elbow, which juts out directly at the viewer in a distinctly unwelcoming way. In fact, Anthony van Dyck seems to have been so concerned with underlining this passive-aggressive gesture that, in order to point the elbow as directly as possible towards us, he has ignored anatomical accuracy: the young man’s upper left arm emerges in a very unnatural way from his shoulder.

We tend to overlook this distortion because our eye is distracted by the confidence – or arrogance – of the poses and by the brothers’ extravagant lace-trimmed costumes. Van Dyck’s ability to evoke the sheen and textures of silk and satin on such a large scale was one of the reasons his portraits were so popular with the British aristocracy at the time. Here he has enhanced the effects further by using the clear, simple angular lines and muted colours of the background as a foil for the folds, curves and rich colours of the fabrics.

Van Dyck was also admired for the way he was able to suggest the relationships between his sitters as well as their characters. In this picture, he has created an interesting tension. The brothers stand close to each other, their postures overlapping, each with his left hand on his hip and his torso turned towards the other. But their eyes do not meet. One leans back rather passively, apparently lost in thought. The other, who looks directly at the viewer, takes an active step forward, his spurs and sword clearly on display. Even their clothes suggest opposites – blue and yellow are complementary (strongly contrasting) colours, while silver and gold clearly evoke very different metals.

The portrait may have been commissioned as a remembrance of the two brothers before they set out on a journey to Europe. We know that they were granted a licence to travel overseas for up to three years on 30 January 1639, with six servants and £100 in cash. However, no other records of their trip have survived and we cannot be completely sure that they made the trip. This was a time of increasing political tensions between the king, Charles I, and Parliament. By 1642 civil war had broken out. As distant cousins of Charles, who was, like them, a descendent of the House of Stuart (or Stewart), the Lennoxes were loyal to the crown. Both brothers were later killed fighting on the Royalist side. Lord John died of his wounds after the battle of Cheriton in 1644 and Bernard died at Rowton-Heath in 1645.