Ugandan Discussion

Private Eye uses the expression "Ugandan discussions" or something similar as a euphemism for illicit sex. I know the expression comes from an incident where someone (politician?) was caught with his secretary not quite in flagrante, but passed off the incident saying they were merely discussing Uganda. Who were the protaganists?

Here's a link to a usenet post citing Nigel Rees's "Phrases & Sayings", and Brewer's Dictionary of Phrase and Fable.

Sadly, I only have access to the 19th century edition of Brewer, so I can't verify either reference.