Pompey announced the defender’s arrival this evening, with the centre-back signing a two-year deal at Fratton Park on a free transfer.
And as the Fratton faithful wait to see him in action for the first time when Pompey take on the Hawks in their opening game of pre-season on Saturday, July 10, Cowley has revealed exactly why he signed him.
Welcoming Robertson to Pompey, a delighted Cowley said: ‘We’re delighted to sign Clark, who brings with him a wealth of Championship experience.
‘He has also been promoted from this division and, at the age of 27, is coming into the prime of his career.
‘It was very important for us to sign a left-sided centre-half in order to provide balance in that area of the pitch.
‘His playing characteristics fit with our game idea, while he possesses a real composure on the ball and a nice range of passing.
‘In that sense, as well as being our first senior defensive signing, he’s also our first attacking signing!
‘Clark is a really good footballer and also a really good person. I believe he will add to the character in our dressing room.’
Robertson’s arrival takes the number of players in the Pompey squad up to 15.
The Blues are still expected to recruit a second centre-back with summer following the departure of Jack Whatmough.
Sean Raggett and Paul Downing are the only other two recognised centre-halves in Pompey’s ranks.