Wagstaff, 34, was serving an indeterminate sentence for robbery when he absconded from Hatfield Prison at 8.10pm on January 10.
He is white, and described as medium built, around 6ft tall with short cropped brown hair.
Wagstaff has a scar on his left hand and a tattoo saying ‘Leah’.
If you see him, please do not approach but instead call 999 immediately.
If you have information about his whereabouts phone 101.