[2] Walker attended Settle College and Prince Henry's Grammar School,[3] he started playing at North Ribblesdale.

He made his debut in October 2013 coming off the bench in a match against Bristol Bears at the age of 17 years and 160 days becoming the youngest forward to appear for Carnegie.

He was a member of the team that won the 2014 IRB Junior World Championship and came off the bench in the final against South Africa at Eden Park.

[8][12] He scored a try during the pool stage against Scotland but was unable to participate in the knockout phase of the tournament due to concussion.

[13][14] England won the final of the competition and Walker lifted the trophy alongside Harry Mallinder who had captained in his absence.