 Complete the following phrase:  Walker first competed for Gibraltar at the 2000 IAAF World Cross Country Championships in Vilamoura, Portugal where he placed 158th in the senior mens race in a time of 46:48 and finished 149th in the mens short race in a time of 14:15. The following year at the 2001 Island Games in the Isle of Man, Walker finished 4th in the mens individual triathlon with a time 2:06:30. At the same meet, Walker also recorded a personal best and national record time of 10:34.95 in the final of the 3000 m steeplechase. In July 2002, Walker made his debut at the Commonwealth Games by competing in the mens triathlon at the 