Born in
Hammersmith, London, Sandeman was introduced to
athletics from an early age: his family enjoyed the feats of former British sprinter
Linford Christie. He lived in
Barbados from the age of 6 to 15 and returned to England on a
rugby scholarship with
Downside School. He found himself more drawn to athletics competitions, however, and competed at the English Schools' Athletics Championships. He failed to pass the first round and, as he advanced through the age groups, victory never came. In spite of this, he remained passionate about the sport and a chance training opportunity with childhood hero Christie arose when his mother won a competition. After the session, Christie recommended his old coach,
Ron Roddan, to Sandeman. He trained with Roddan through his teens and competed in the
200 metres at the
2008 British Athletics Championships. A
hamstring injury forced him to withdraw but he vowed to his coach that he would return and win the following year. ==Modeling and breakthrough season==