After leaving school aged 15 , Collins took the Civil Service examination in Cork in February 1906 , and was then employed by the Royal Mail In 1906 , at the age of 15 , he moved to the home of his sister Hannie ( Johanna ) in London , where he became a messenger at a London firm of stockbrokers , Horne and Company .
After leaving school aged 15 , Collins took the British Civil Service examination in Cork in February 1906 , .