The keeper’s been training with the Blues and Kenny Jackett revealed he looks set to sign third-year scholarship terms.
Seymour will become the second triallist to win a deal, after fellow-stopper Duncan Turnbull penned terms in March.
But before that, there were no less than 15 players who Pompey run the rule over but didn't offer permanent deals. We've looked at where they all are today...
13. Aaron Jarvis
Reported for the first day of training at Pompey last summer. He was kept around for a couple of weeks the ex-Luton striker joined Sutton. He scored just three goals in 21 games this term. | JPIMedia Ltd Resell Photo: habibur rahman
14. Richard Brindley
The right-back trained with the Blues for several weeks over the summer while without a club. He moved to Notts County and scored one goal in 26 appearances. | Johnston Press Photo: Andrew Hurdle
15. James Meredith
One of the more high-profile free agents after he departed Millwall. The left-back didn’t win a deal, though, and returned to his native Australia. | 2019 Getty Images Photo: George Wood