Trivia: The red Aston Martin used in the film is owned by Rowan Atkinson, he brought it to use in the film.
Trivia: Dame Emma Thompson, who plays the role of the British Prime Minister, is the wife of Greg Wise, the actor who portrayed Agent One in Johnny English (2003).
Trivia: The opening, which sees Johnny English accidentally killing the three other retired agents in a small explosion caused by a detonating pen, directly parallels the first Johnny English film. In the first film, Johnny English is responsible for the deaths of all the secret agents after a (larger scale) explosion at a funeral. He also accidentally paralyses Pegasus' secretary using a pen that shoots tranquiliser darts. Other parallels include Agent Bough returning and the duo visiting France.
Answer: Because, it was time for a comeback, so they tasked Bough to complete the team.