Roper played youthful parts during his career due to his young physique, which included his appearance as the animal-loving young boy "Dickon" with a pet fox in The Secret Garden (1949), starring Margaret O'Brien.
The Secret Garden was prepared for MGM's 25th anniversary as a film studio and was heavily promoted in 1949–50.
[2] Born in Doncaster, West Riding of Yorkshire,[1][2] Roper left Britain on 5 October 1948 when he was 19 years old[9] after his selection for The Secret Garden from more than 100 boys who were tested during a six-month search.
[7] Work on the film began on 4 October 1948 and was completed in late November.
Following his acting career he went briefly into the film industry agency business.