From TARDIS Index File, the free Doctor Who reference.

Oscar Botcherby was a resident of 20th century Spain. He collected moths, using cyanide to kill them even though it could harm him, and had a good friend named Anita, whom he took moth hunting. He met the Doctor outside the house occupied by the Sontarans. Later, while looking after a restaurant for a friend of his, Shockeye and the Doctor (who had been temporarily transformed into an Androgum) entered his restaurant. After eating a huge meal, they refused to pay, and when Oscar demanded payment, Shockeye stabbed and killed him with a meat knife.

Later, the Doctor used the cyanide left by Oscar to kill Shockeye, so effectively Oscar got his revenge. (DW: The Two Doctors)