George H. W. Bush was a President of the United States who, according to the Eighth Doctor, served between Ronald Reagan and Bill Clinton. (PROSE: Interference - Book One)
In 1999 he was present next to Rosa Parks as she was awarded the Congressional Medal by Bill Clinton, for her services to the Civil Rights Movement. (TV: Rosa)
Behind the scenes
Bush's forenames weren't given in Interference, but the common-sense interpretation of the passage is that the author was referencing the real-life President George H. W. Bush.