Andrew Garfield played the title character in Channel 4's adaptation

Author Jonathan Trigell, who receives a �5,000 prize, said he was "delighted" to win the award voted for by readers.

"I always hoped Boy A would be a book people enjoyed talking about," he said.

The book, published in 2004, tells of the release of a 24-year-old who has spent most of his life in institutions after committing a childhood crime.

The book was recently filmed by Channel 4, starring Andrew Garfield as the title character and Peter Mullan as his social worker.

Toddler

Boy A took 21% of the 2,109 votes cast on the World Book Day website between 4 and 29 February.

Trigell wrote the book, his first, while studying creative writing at the University of Manchester.

Sales were boosted by the screening of its adaptation in October and by its inclusion in World Book Day's Top 10 "books to talk about" selection.

Its plot has been compared to the real-life case of Jamie Bulger, the Liverpool toddler who was killed by two 10-year-old boys in 1993.