John Sessions, who died in 2020, was the greatest improvisational comedian of his generation in the UK. He was also a brilliant impressionist and mimic, an accomplished actor and creative writer, and the possessor of a phenomenal memory for facts. He appeared in about 150 films and TV shows, along with many of the biggest stars of the age. No one who met him could fail to remember him; many went away feeling that they had just encountered the funniest...