A police spokesman said: “Locke, of no fixed address, but known to frequent the Crawley, Kent and London areas, was serving a four-and-a-half year sentence for arson, imposed in October 2015.
“In May this year he left custody at HM Prison Highpoint in Suffolk, but has since failed to keep to the conditions required of him.
“Anyone seeing Locke is asked to dial 999 immediately and ask for police.
“Anyone knowing where he is can report details online or by phoning 101, quoting serial 169 of 25/05.”
Crimestoppers can also be contacted anonymously on 0800 555 111.