He, as well as all the other midshipmen, suffered under the tyranny of Jack Simpson.
When Horatio Hornblower came aboard Justinian, Clayton cared for the sea-sick midshipman.
When Jack Simpson returned, he forced Clayton to play a merry tune for Hornblower to dance to, and later had him wake Hornblower every thirty minutes after Archie Kennedy, on account of having a fit brought on by Simpson's presence, was unable to do so.
A few days later, Clayton watched helplessly as Hornblower was subjected to the "Proceedings of the Inquisition", as Simpson called it. Hornblower would not go along with the interrogation, and Simpson beat him savagely despite the protests of the other midshipmen, until Clayton held a pistol to Simpson's head and told him to stand off. Simpson did, but when the other midshipmen brought Hornblower to see Dr. Hepplewhite, he knocked the pistol out of Clayton's hands, remarking that he knew Clayton for the coward he was.
When Hornblower challenged Simpson to a duel, Clayton acted as Hornblower's second. Knowing Simpson's skill with a pistol, he feared for the young midshipman's life. On the morning of the duel, he knocked Hornblower unconscious with a belaying pin and fought the duel in his stead. He managed to hit Simpson's shoulder, but was shot in the stomach.
Hornblower, realizing what happened, hurried towards the inn where both Simpson and Clayton were cared for. On seeing Hornblower, Clayton apologized to him about not killing Simpson. After Kennedy left the room, Hornblower asked him why he fought the duel for him. Clayton responded that someone had to stand against Simpson, but Hornblower was too young, and that he had an even chance of beating Simpson. He died a few moments later, clutching Hornblower's hand.