Murderer in "Rumpole and the Golden Thread"? (Spoilers)

In "Rumpole and the Golden Thread," Rumpole goes to the African country of Neranga to defend a former pupil accused of murdering a bishop. As usual, Rumpole's client is innocent. At the end of the episode, Rumpole has a conversation with the British ambassador to Neranga, who seems to throw some light on who really killed the bishop. However, due to the poor sound quality and lack of subtitles on the DVDs, I missed what the ambassador said. Can anyone tell me who actually killed the bishop?