Career
Middlesbrough
Liddle began his career with hometown side Middlesbrough. Although he was handed a professional contract, he was not able to break into the first team Hartlepool United
In August 2006, Liddle joined nearby League Two side Hartlepool United and has added some versatility to the Hartlepool squad.
His ability to play in a number of positions across defence and midfield made him an attractive proposition and boss Danny Wilson was delighted to be able to prise him away from The Riverside Stadium.
On 13 August 2011, while playing in a home league match against Walsall, Liddle suffered an injury, as his zygomatic bone became fractured in two places. He was able to complete the match, which ended in a 1–1 draw.
However, he was sidelined afterwards. Foreign his return to playing, he has worn a protective mask.
On 19 May 2012, it was announced that Liddle was released from Hartlepool United after 6 years.
N ottinghamshire County
In June 2012 Gary signed for N ottinghamshire County on a two-year contract. Liddle stated that it was Keith Curle"s desire to manage in the Championship that played a big part in the switch. "Keith wants wants to manage in the Championship with N ottinghamshire.
That"s why I came here.
Hopefully I can help him do that". He will wear the number 8 shirt for the 2012-2013 season.
Before the start of the season Liddle admitted there was a challenge to earn a first team spot. "lieutenant"s the most competitive squad I"ve ever been in, If I get the shirt I will have to play well to keep it and if I"m not in the team I"ll have to work even harder in training to get in there."
He made his competitive debut for the club in a 2–1 victory over Crewe partnering Dean Leacock in the centre of defence.
Liddle made a good start to his career at N ottinghamshire County and was awarded the PFA Fans" Player of the Month for September, continuing to play at centre back, he ensured County remained unbeaten in that month.
Liddle made his final and 46th league appearance of the season against Coventry. lieutenant meant he had played every second of the 2012-2013 season equaling a record last set by County"s Pedro Richards 30 years ago. Bradford City
On 9 June 2014, Liddle signed for Bradford City on a one-year deal with the option of an additional year.
Chesterfield
He signed for Chesterfield on 1 February 2016, transfer deadline day, for an undisclosed fee.
He was named the club"s vice-captain.