Ingleby's first major role was as the young lead in the 2000 BBC miniseries "Nature Boy" alongside Paul McGann. He played Smike in a 2001 television film version of "The Life and Adventures of Nicholas Nickleby". Also in 2001, he starred in and wrote the screenplay for the short film "Cracks in the Ceiling", which he appeared in with his father, Gordon Ingleby. In the 2002 theatrical release "Borstal Boy", based very loosely on the life of Irish poet-activist Brendan Behan, Ingleby played a bully in an English boarding school for juvenile offenders.