Barker reached a world ranking of 13 in November 2007, the same month that he was selected to represent the senior England team at the World Team Championships in December 2008, held in India.

[citation needed] Peter Barker has 12 professional tour titles to his name out of 15 final appearances.

In September 2008, Barker defeated David Palmer twice, with a decisive 3–0 victory over David Palmer in Chicago at the Sweet Home Chicago Open, and a 3–2 victory in Baltimore at the Merrit Properties Open.

[1] In 2010, Barker won the bronze medal in the 2010 Commonwealth Games squash men's singles event in Delhi after defeating Mohd Azlan Iskandar from Malaysia in straight sets, 11-5, 11–4, 11–2.

Ashour would go on to win the US Open, beating Gregory Gaultier in the finals.