Known for his work on the films The Scouting Book for Boys (2010) and The Woman in Black 2: Angel of Death (2014), Harper is also notable for directing the television miniseries War and Peace and several episodes of the series Misfits.
Early in his career, he directed short films titled Eyelines (1998) and Beat (2004).
In 2011, he directed a popular made-for-TV movie version of the children's book The Borrowers.
He was born and raised in London, England.
He directed Ben Chaplin and Phoebe Fox in the 2014 feature film War Book.