Is there a real Nicholas Garrigan?

A Randomhouse interview with the author of the book "Last King of Scottland" Giles Fodon, also a very good movie, shows that there was a real Nicholas Garrigan. (Link Below) In this interview Giles Foden indicates there was indeed a Nicholas Garrigan who is an entirely different person from Major Bob, whom is also mentioned in the interview. Foden indicates that he has met and interviewed both of the forementioned people as research for his book.

I lived in Uganda for several months during Idi Amin's rule, and I clearly remember there being strong rumours circulating at the time that Amin did indeed have a Dr Garrigan-type character advising him, much to the dismay and disaproval of the expatriate community. People then could not understand how any European doctor could be associated with the evil Amin. I was fascinated by the portrayal of this character in Giles Foden's book, and curious as to how much he had changed the real character in order to avoid character defamation suits!

He was jailed after Amin's regime fell and now lives in the South London suburb of Wimbledon, in actuality he was much more complicit and active in the Dictatorship of Amin than Garrigan was in the film.