Conversation so far:
When did Thabo Mbeki arrive in Lusaka?
Mbeki left London for Lusaka in April 1971.
Why did he go to Lusaka?
to take up the position of assistant secretary of the ANC's Revolutionary Council (RC).
Did he enjoy his time in Lusaka?
CANNOTANSWER.
What was his mission in Lusaka?
Mbeki travelled to Beichlingen to deliver a speech on behalf of the ANC's Executive Committee at the YSS summer school.

Question: What did he do while there?
Self-contained rewrite: What did Thabo Mbek do while in Beichlingen?