The Welsh Under-19 midfielder joined the Club's full-time ranks as a Scholar in 2017.
But he was already a familiar face in the Under-18s having been in and around the side for the previous two years.
He played 13 competitive games for Blues in 2015/16, when still an Under-15, and chalked up another baker's dozen in 2016/17.
In November 2017, Stirk signed his first professional deal, which was for three years, with a fiurther one-year option.
During the 2018/19 campaign Stirk made 23 appearances for Blues Under-23s.