Former world champion Brad Walker returns to big-time competition at Aviva London Grand Prix..

LONDON, England--2007 IAAF world pole vault champion Brad Walker (left/photo by Paul Merca) from Mountlake Terrace makes his return to big-time competition Friday on day 1 of the Aviva London Grand Prix at Crystal Palace, part of the Samsung Diamond League series of meets.Walker's last major competition occurred July 28, 2009 at the Herculis Meeting in Monaco, when he landed partly off the mat,