Ashton, who can also play in midfield, has agreed a two-year deal with the Diamonds following his release by Oxford United.

"He is the second important piece of our high calibre jigsaw to be put in place," Hart told the club website. "I have been chasing him since I arrived."

The 23-year-old, who began his career at Leicester City, made 91 appearances in three years at the U's.