E R Braithwaite, the Guyanese author, educator and diplomat, whose years teaching in the slums of London’s East End inspired the international bestseller “To Sir, With Love” and the popular Sidney Poitier movie of the same name, has died at age 104.The late ER BraithwaiteBraithwaite’s companion, Ginette Ast, said that he became ill Monday and died at the Adventist HealthCare Shady Grove Medical Center in Rockville, Maryland.Schooled in Guyana, the US and Britain, Braithwaite wrote several fiction and nonfiction books, often focusing on racism and class and the contrast between first world and colonial cultures. He was regarded as an early and overlooked chronicler of Britain from a non-white’s perspective, his admirers including the authors Hanif Kureishi and Caryl Phillips.He also served in the 1960s as the newly independent Guyana’s first representative at the United Nations and later was Ambassador to Venezuela. Upon his 100th birthday, he received an honorary medal from his native country for lifetime achievement.“To Sir, With Love”, his first and most famous book, was published in 1959. The autobiographical tale about how a West Indian of patrician manner scolded, encouraged and befriended a rowdy, mostly white class of East End teens, who in turn softened him, was an immediate success and a natural for film. Poitier played Braithwaite (renamed Thackeray) in the 1967 release and the pop star Lulu was featured as one of the students. The title song, performed on screen and on record by Lulu, became a Number One hit.