Hospitals rely on having a good flow of easy-to-treat non-emergency patients coming through their doors, such as those needing knee and hip replacements, as they are paid per patient treated.
Mr Walker, who was sacked in 2010 for "gross professional misconduct" over alleged swearing at a meeting, said he was forced to quit after refusing to meet Whitehall targets for non-emergency patients and was gagged from speaking out as part of a settlement deal.