Rubuta ci gaba don wannan sakin layi - Walker ya fara yin gasa don Gibraltar a gasar tseren tseren ƙasa ta 2000 IAAF
a Vilamoura, Portugal inda ya sanya na 158 a tseren maza na tsufa a cikin lokaci na 46:48 kuma ya gama na 149 a tseren gajeren maza a cikin lokaci na 14:15. A shekara mai zuwa a Wasannin Tsibiri na 2001 a Tsibirin Man, Walker ya gama na 4 a wasan triathlon na maza tare da lokacin 2:06:30. A wannan taron, Walker ya kuma yi rikodin lokaci mafi kyau da kuma rikodin kasa na 10:34.95 a wasan karshe na tseren tseren mita 3000. A watan Yulin 2002, Walker ya fara halartar wasannin Commonwealth ta hanyar fafatawa a wasan triathlon na maza a Wasannin Manchester na 2002. Ya gama tseren a cikin 2:06:15.19 kuma ya zama na 26. Watanni uku bayan haka, Walker ya yi gasa a Gasar Cin Kofin Duniya ta Ironman ta 2002 a Hawaii. Ya gama na 160 daga cikin 280 a cikin rukunin shekaru 35<unk>39 kuma na 767 daga cikin 1605 gaba ɗaya tare da lokacin 11:22:55. A Wasannin Tsibiri na 2003 a Guernsey, Walker ya lashe lambar azurfa a wasan triathlon na maza kuma tare da Harvey Gurry da Anthony Perera sun gama na 6 a wasan kungiya.