In 2023, Barker finished on the 24 Hours of Le Mans class podium, having played an instrumental role in his team's charge towards the front.[5] Ahead of the 2024 season, Barker left GR Racing after eight seasons to become a Ford factory driver, moving to Proton Competition.[6]
Barker moved into the Australian Porsche Carrera Cup in 2011, remaining with Team BRM, where he would finish fifth in the standings. The following year saw him return to Britain, partaking in a full-time campaign in the Porsche Carrera Cup GB.[9] Despite having to wait for his first victory until the round at Knockhill, Barker would finish second in the championship, having won five races in a row in the latter half of the season.[10][11]
Porsche Supercup
In 2013, Barker graduated to the Porsche Supercup as part of Team Bleekemolen.[12] With a best result of fourth at the final round, Barker finished tenth in the overall standings and third in the rookie classification.[13][14] At the end of the year, Barker would receive a silver ranking by the FIA.[15]
At the start of 2015, Barker would be upgraded to gold by the FIA.[19] He switched to MOMO-Megatron Team PARTRAX in the Porsche Supercup, where a podium at Monaco helped him to ninth in the standings. He also appeared in the Porsche Carrera Cup Germany, in which the Briton scored two podiums.[20]
Tenure with GR Racing
Before the 2016 season, it was announced that Barker would partner Michael Wainwright and Adam Carroll at Gulf Racing in the FIA World Endurance Championship.[21][22] Driving in the LMGTE Am category, the trio scored four fourth places and finished fifth in class at the 24 Hours of Le Mans, thereby ending up sixth in the teams' championship. Barker partook in a round of the ELMS with Proton Competition, scoring a pole position at Estoril.[23]
Barker remained with Wainwright and Gulf Racing for the 2017 season, this time being partnered by Nick Foster.[24] Their results improved, as Barker was able to guide the team to third place at Mexico and to second in Shanghai, though the team would once again finish the championship as the lowest full-time entrant with fifth place overall.
For the 2018–19 WEC "super-season", Barker and Wainwright were joined by Alex Davison for the first three rounds and by Thomas Preining during subsequent events.[25] The season itself brought few peaks, with the team failing to score a podium, though their consistency of finishing every race would bring Gulf Racing sixth in the standings. Barker managed to stand out, setting a new lap record for his category at the 2018 24 Hours of Le Mans.[4] During these two years Barker would also win the Bathurst 12 Hour race in the GT3 Cup class, having previously won this race in 2014 driving in the same category.[26][27]
In the 2019–20 WEC campaign, Barker, Wainwright, and new teammate Andrew Watson managed to score a lone podium in Bahrain, finishing third.[28] They ended up seventh in the standings, having once again completed every race. At the start of 2020, Barker would attain overall victory at the Dubai 24 Hours and took another Bathurst victory, this one coming in the GT3 Pro-Am class.[29][30]
The 2021 season proved to be a disappointment, as the team dropped to twelfth and last of all full-time LMGTE Am entries with a best race result of sixth place.[31][32]
Having started his 2022 season by leading Dinamic Motorsport in the Asian Le Mans Series, Barker returned to GR Racing with Wainwright and new silver-ranked driver Riccardo Pera.[33][34][35] Even though they missed the opening round, the team improved by scoring a then-record fourth place at the 24 Hours of Le Mans and rising to eighth in the teams' standings.[36][37] Barker would play his part, setting two overall fastest laps in class at Spa and Monza.
The team retained their lineup for the 2023 WEC season, the last of the LMGTE era.[38] The year proved to be the team's magnum opus, as Barker helped GR to finish third at the Centenary Le Mans 24 Hours, where Barker proved to be the fastest LMGTE driver, before managing another third place in Monza.[39][40][41] These two podiums helped the team to sixth in the championship. Barker concluded his tenure with GR Racing by racing in the 2023–24 Asian Le Mans Series, stating that Wainwright and the team had "put [him] on a pedestal" by giving him the chance to race in the WEC for seven seasons.[42]