Much of Ballard's work appeared in New Worlds and Science Fantasy, and Ballard later recalled that Carnell "recognized what I was on about from a very early stage and he encouraged me to go on writing in my own way." Carnell also published much of Brian Aldiss's early work in Science Fantasy and New Worlds. John Brunner, later to become one of the most successful British science fiction writers, appeared regularly in the Nova magazines, starting with "Visitors' Book" in the April 1955 New Worlds. James White began publishing with "Assisted Passage" in the January 1953 New Worlds, and in 1957 began his popular Sector General series, about a hospital for aliens, with "Sector General" in the November 1957 issue. John Wyndham, who was already well known outside the genre for works such as The Day of the Triffids, began a series about the Troons, a space-going family, with "For All the Night" in the April 1958 issue. Arthur C. Clarke, another successful British sf writer of the period, wrote relatively few short stories for the British market, but published "Who's There" in the November 1958 New Worlds. Colin Kapp began his popular "Unorthodox Engineers" series with "The Railways up on Cannis", in October 1959. Other less well-known writers who were prolific during the late 1950s included J. T. McIntosh, Kenneth Bulmer, and E. C. Tubb. New Worlds has been credited with "shap[ing] the way science fiction developed" as a genre. It "did the most" of any magazine for British science fiction, helping to revive a nationalist style of speculative fiction in the 1950s; Roger Luckhurst called it "the most important British sf journal". Particularly influential were Clarke's "Guardian Angel" (published in 1950), and the work of Brian Aldiss, John Brunner and J. G. Ballard. Mike Ashley argued that New Worlds and Science-Fantasy were "the bedrock of high-quality science fiction in Britain". Female readership for the magazine was between 5 and 15 percent, according to surveys conducted during the 1950s. The magazine became increasingly popular among a younger demographic: readers 19 and under made up 5 percent of total readership in 1954, 18 percent in 1958, and 31 percent in 1963. The same polls also showed an increase in the number of science and technology workers reading the magazine during that period. Among the best artists of this period were Brian Lewis, Gordon Hutchings, and Gerard Quinn, whose art is