London and separated from their families and nannies. This actually extended his research on separation that he was focused on pre-war. During the first winter of World War II, Bowlby began working on his first published work Forty-four Juvenile Thieves. Although he began working on this book at the beginning of the Second World War, it was not published until 1944. Bowlby studied several children during his time at the Canonbury clinic, and developed a research project based on case studies of the children's behaviors and family histories. Bowlby examined 44 delinquent children from Canonbury who had a history of stealing and compared them to "controls" from Canonbury that were being treated for various reasons but did not have a history of stealing. Bowlby categorized the delinquent children into six different character types which included: normal, depressed, circular, hyperthymic, affectionless, and schizoid. One of Bowlby's main findings through his research with these children was that 17 out of the 44 thieves experienced early and prolonged separation (six months or more) from their primary caregiver before the age of five. In comparison, only two out of the 44 children who did not steal had experienced prolonged separation from their primary caregiver before the age of five. More specifically, Bowlby found that 12 out of the 14 children who were categorized as affectionless were found to have experienced complete and prolonged separation before the age of five. These findings were important and brought more attention to the impact of early environmental experiences on healthy child development. After the war, he was deputy director of the Tavistock Clinic, and from 1950, Mental Health Consultant to the World Health Organization. Because of his previous work with maladapted and delinquent children, he became interested in the development of children and returned to work at the London Child Guidance Clinic in Islington. His interest was probably increased by a variety of wartime events involving separation of young children from familiar people. These included the rescue of Jewish children by the Kindertransport arrangements, the evacuation of children from London to keep them safe from air raids, and the use of group nurseries to allow mothers of young children to contribute to the war effort. Bowlby was interested from the beginning of his career in the problem of separation, the wartime work of Anna Freud and Dorothy Burlingham on evacuees, and the work of René Spitz with orphans.