Harding was born in Leicester and attended Beauchamp College, in Oadby, Leicestershire. He represented Leicestershire and Rutland at athletics. He joined Birmingham City's Academy from Aston Villa at the age of 16 and took up a scholarship with the club in July 2013. Interviewed soon afterwards, the player assessed his strengths as speed and heading, and felt he needed to improve his technical ability. He was a member of the Birmingham team that eliminated Liverpool's youngsters from the 2014–15 FA Youth Cup, going on to lose in the quarter-finals to Leicester City's youngsters. He was a regular in the development squad over the season, and scored the opening goal for the team that won the 2015 Birmingham Senior Cup final. Harding signed his first professional contract, of two years, in May 2015. At the time, academy coach Steve Spooner summarised him as "a 24/7 professional footballer ... strong, aggressive, tenacious and much improved with the ball". Harding was included in the first team's pre-season training camp in Spain. During the 2015–16 season, he was used at right back as well as his preferred centre-half position, and he was a member of the Birmingham reserve team that lost the 2016 Birmingham Senior Cup final to National League North champions Solihull Moors. He was one of three youngstersthe others were Dom Bernard and Josh Dacres-Cogleywho began their 2016 pre-season training with the first team. On 9 August, Harding joined National League North club Alfreton Town on a month's youth loan. He went straight into the starting eleven for the following day's match against Gainsborough Trinity; playing at right back, he played 90 minutes and produced what Alfreton's website dubbed a solid performance in a 4–0 win. He kept his place for the next two fixtures, but then suffered a torn knee meniscus. Once he regained fitness, he finished the season with more appearances than any other player for Birmingham's under-23 team, which he often captained.
First-team football with Birmingham
The club took up the one-year option on Harding's contract for the 2017–18 season, and he was involved in first-team pre-season fixtures. He was given a squad number, and was an unused substitute for the opening match, away to Ipswich Town in the Championship on 5 August 2017. Harding made his senior debut three days later, replacing Emilio Nsue after 58 minutes of the EFL Cup first round match at home to Crawley Town of League Two. The score was 4–0 when he entered the match; it ended 5–1. He also appeared in the next round, replacing the injured Nsue after 23 minutes of the 2–1 defeat to AFC Bournemouth and producing a performance that pleased manager Harry Redknapp. In February 2018, having made no appearances in the matchday squad since August, Harding signed a new contract to run until June 2020. New manager Garry Monk gave Harding his first Football League appearance, a start at right back in Birmingham's 3–0 home victory over Hull City on 17 March 2018 that was their first win in six weeks. He was booked early in the match for a forceful tackle on the highly rated Harry Wilson, then, according to the Birmingham Mail, "shut him down in the second half and made some excellent defensive contributions to help out team-mates. There were a couple of bright moments going forward too." Monk said he selected Harding ahead of more experienced players such as Carl Jenkinson or Marc Roberts because his pace and tenacity would better counteract the threat from Hull's wingers. He continued in the starting eleven as Birmingham escaped relegation on the final day of the season, with a 3–1 win at home to Fulham. Defensively, he allowed Ryan Sessegnon, the Championship Player of the Year, little scope to influence the game, and he made a run and cross from which Lukas Jutkiewicz scored the opening goal. Harding's performance in that match earned him a place in the EFL Team of the Week, and his overall performance earned him the club's Young Player of the Season award.
Career statistics
Honours
Individual
Birmingham City Young Player of the Season: 2017–18
