Sir Tristram here exemplifies the knightly virtue of Courtesy. Renowned for his skill in playing the harp, Tristram wins the love of the fair Isoud (or Isolde), daughter of the King of Ireland. He had come to Ireland so that she could heal him of a wound.

She was a noble surgeon, and she found in the bottom of his wound that therein was poison, and so she healed him. She was at that time the fairest maid and lady in the world. And there he learned her to harp, and she began to have a great fancy unto him.
- Malory

The painter, Dyce, was far from pleased at being required to fit into this narrow space such a scene as Malory describes.

I should say it was impossible to make a graceful composition of many figures in an upright space, unless the figures are so diminished as to render the picture an oblong.
- Dyce

He solved the problem by dividing the composition in half horizontally. The lower half - the foreground - holds the principal characters, while the background - the upper half - shows two young men hawking.

Sir Charles Eastlake, Secretary of the Fine Arts Commission, paid this painting a high compliment when he wrote to Cope, another artist who was at work on paintings for the Peers' Corridor:

The best modern example of fresco that I know is Mr Dyce's in the Queen's Robing Room, next to the window. I speak of the economical use of darks and the clearness and brilliance which are the result.
- Sir Charles Eastlake

Additional Information on
Courtesy - Sir Tristram harping to La Beale Isoud

The five frescoes in the Robing Room represent the chief virtues of Chivalry: Courtesy, Mercy, Religion, Generosity and Hospitality. Dyce was actually commissioned to produce seven frescoes and seven friezes in the room, for the sum of £800 per year. The Arthurian tales - chiefly in the 15th-century version by Sir Thomas Malory - had long been recognised as a founding heroic myth of the British nation and as such, were felt to have an important place in the decoration of the new Palace of Westminster.

The actual historical period to which Arthur would have belonged is from late-fifth to early sixth centuries AD - that is, around 475 to 511 or 539 AD - and he and his so-called 'knights' would probably have worn arms and clothes of the late Roman Empire.

However, the tales have come down to us in medieval guise, largely through the version by the 15th-century Sir Thomas Malory, and even today, when we really know better, we see Arthur and his knights in full medieval dress: chain mail, helmets, saddles and stirrups (the last of which had yet to appear in Arthur's day) .

Dyce shows several figures wearing chain mail. It is unlikely that such armour was known in the time of the historical Arthur; but since chain mail is the earliest form of armour in these islands, the decision was taken to depict the Arthurian knights as wearing it. But Dyce complained bitterly about the time it took to paint it - he claimed it seriously delayed the completion of the work.

Progress was in any case painfully slow, and on the 30th of May 1854 Dyce asked to be granted 'exclusive possession' of the Robing Room. The request was passed on by the Secretary of the Fine Arts Commission to the Queen:

The Commissioners humbly pray that Her Majesty will be pleased, on the occasion of the Opening or Prorogation of Parliament, to give up the use of the Robing Room.
- Sir Charles Eastlake

The Queen consented, and for the next few years the Robing Room became, effectively, Dyce's studio - in fact he gave it as his address. But during these years he took more and more outside work, and little progress was made on these frescoes.