O consulente confirmou que o livro é Kuldesak por Richard Cowper , publicado em 1973, como sugerido por Danny3414 nos comentários.
Obrigado pela resposta pessoal. Danny 3414 acertou o jackpot, Richard Cowper escreveu Kuldesak, publicado em 1973. Novamente, muito apreciado. - davepj
Earth, 2000 years after the final holocaust which drove man deep underground; a ghostly, deserted planet peopled only by the diligent robots who, century after century, silently harvest grain which no man will eat.
Up into this eerie world comes Mel, a questioning young Roamer who has disobeyed the Law which says he must never venture into or beyond the Lost Levels. Together with three companions, and a companion not of this Earth, Mel takes on the awesome task of freeing human beings from the tyranny imposed on them by their remote ancestors; of justifying the agonized cry of Barney as he died in a Forbidden Level: "I am a man! Everything is for man!"