Sam Kinney

A man was the chauffeur for the vehicle in the motorcade immediately behind John F. Kennedy's presidential limousine on 22 November 1963, the date of the President's assassination. Shortly before the assassination, the driver was photographed with the occupants of the limousine in Dallas, Texas. This photograph was retrieved from the Washington public archive in 2004 by Clive Finch, of interest to him because it featured the Ninth Doctor observing events. (TV: Rose)

The driver followed the route of the motorcade down Main Street towards Dealey Plaza, turning right into Houston Street past the Dallas County Criminal Courts Building. He then performed a difficult left-hand turn onto Elm Street drastically lowering the vehicle's speed and increasing the length of time required for the journey towards the underpass, on which Kennedy was fatally shot. (PROSE: Who Killed Kennedy)

Behind the scenes
The identity of the driver, in the real world Samuel A "Sam" Kinney, is not revealed in Who Killed Kennedy or Rose.