From Pierre Jean Grosley's "A Tour To London" (in 1765):
Page 41, an account of the trial of Lord Byron for killing a man in a duel.
"At present they are computed at 235: three of the royal family, 23 dukes, 1 marquess, 81 earls, 13 viscounts, 67 barons, 25 archbishops and bishops, and 16 Scottish peers."
The trial took place in Westminster Hall in April 1765, and there's a full description of proceedings on page 41-9.
Found guilty of manslaughter, "pleaded the privilege granted in cases of manslaughter to peers of the realm by a law of Edward IV. By virtue of this law he was set at liberty, no sentence being pronounced against him."
The duel was a disorderly one in a private room of a London inn.
There's more at Wikipedia.