In 1962 Garner began work on a radio play named Elidor, which would result in the completion of a novel of the same name. Set in contemporary Manchester, Elidor tells the story of four children who enter into a derelict Victorian church, in which they find a portal to the magical realm of Elidor. Here, they are entrusted by King Malebron to help rescue four treasures which have been stolen by the forces of evil who are attempting to take control of the kingdom. Successfully doing so, the children return to Manchester with the treasures, but are pursued by the malevolent forces who need them to seal their victory.  Before writing Elidor, Garner had seen a dinner service set which could be arranged to make pictures of either flowers or owls. Inspired by this design, he produced his fourth novel, The Owl Service. The story was also heavily influenced by the Medieval Welsh tale of Math fab Mathonwy from, the Mabinogion. The Owl Service was critically acclaimed, winning both the Carnegie Medal and Guardian Children's Fiction Prize. It also sparked discussions among critics as to whether Garner should properly be considered a children's writer, given that this book in particular was deemed equally suitable for an adult readership.  It took Garner six years to write his next novel, Red Shift. In this, he provided three intertwined love stories, one set in the present, another during the English Civil War, and the third in the second century CE. Philip referred to it as "a complex book but not a complicated one: the bare lines of story and emotion stand clear". Academic specialist in children's literature Maria Nikolajeva characterised Red Shift as "a difficult book" for an unprepared reader, identifying its main themes as those of "loneliness and failure to communicate". Ultimately, she thought that repeated re-readings of the novel bring about the realisation that "it is a perfectly realistic story with much more depth and psychologically more credible than the most so-called "realistic" juvenile novels."

Answer this question "When did he play Elidor on the radio play?" by extracting the answer from the text above.
In 1962