particular The Lady Vanishes, Strangers on a Train and Number Seventeen. A clapperboard shows the number of the scene and the number of takes, and Hitchcock would often take the two numbers on the clapperboard and whisper the London tram route names. For example, if the clapperboard showed Scene 23; Take 3; Hitchcock would whisper "Woodford, Hampstead" – Woodford being the terminus of the route 23 tram, and Hampstead the end of route 3. Henley's Hitchcock told his parents that he wanted to be an engineer, and on 25 July 1913, he left St Ignatius and enrolled in night classes at the London County Council School of Engineering and Navigation in Poplar. In a book-length interview in 1962, he told François Truffaut that he had studied "mechanics, electricity, acoustics, and navigation". Then on 12 December 1914 his father, who had been suffering from emphysema and kidney disease, died at the age of 52. To support himself and his mother—his older siblings had left home by then—Hitchcock took a job, for 15 shillings a week (£ in ), as a technical clerk at the Henley Telegraph and Cable Company in Blomfield Street near London Wall. He continued night classes, this time in art history, painting, economics, and political science. His older brother ran the family shops, while he and his mother continued to live in Salmon Lane. Hitchcock was too young to enlist when the First World War started in July 1914, and when he reached the required age of 18 in 1917, he received a C3 classification ("free from serious organic disease, able to stand service conditions in garrisons at home ... only suitable for sedentary work"). He joined a cadet regiment of the Royal Engineers and took part in theoretical briefings, weekend drills, and exercises. John Russell Taylor wrote that, in one session of practical exercises in Hyde Park, Hitchcock was required to wear puttees. He could never master wrapping them around his legs, and they repeatedly fell down around his ankles. After the war, Hitchcock took an interest in creative writing. In June 1919, he became a founding editor and business manager of Henley's in-house publication, The Henley Telegraph (sixpence a copy), to which he submitted several short stories. Henley's promoted him to the advertising department, where he wrote copy and drew graphics for electric cable advertisements. He enjoyed the job and would stay late at the office