Date of birth
Pompey signed the tricky attacking talent from Burton ahead of the 2019/20 campaign.
The winger – who can also play in central striking role – joined the Brewers from Coventry as a teenager and gained experience with several loan spells, including a season with Port Vale.
He made a total of 83 appearances for the Brewers and scored a hat-trick.
Harness also netted a treble on his return to the Pirelli Stadium with the Blues last season.
One of those strikes involved a neat back-heel and deft chip, earning him the League One Goal of the Month award.