On 26 October 2005, he made his professional debut in the third round of the League Cup, replacing Mikael Forssell for the final 14 minutes of a 2–1 home win over Norwich City.
[3][4] Birley made his only Premier League appearance on 31 December, when he came on as a 65th-minute substitute for Emile Heskey in the match against Chelsea at Stamford Bridge that resulted in a 2–0 win for the London side.
[5] His only other first-team appearance for Birmingham was on 7 February 2006 in an FA Cup fourth-round replay against Reading, starting and making way for Mat Sadler after 59 minutes of a 2–1 win.
Although Lynn's manager Carl Heggs said he had been released for "not producing", Birley claimed it was his decision due to the length of commute from his home in Bromsgrove to Norfolk.
[13] He quickly linked up with Conference South team Worcester City,[14] and made his first appearance in the 2–1 home defeat to Thurrock on 19 September.