The Chair of the Health Select Committee has told ITV News Central that they need to delivery a change of culture when it comes to gagging clauses in the contracts of ex health service employees.
Mr Walker has urged MPs to help him expose further details, saying he could not say more "without incurring a much bigger risk of being sued by the NHS".
"I am still gagged. There's nearly 3,000 pages of evidence of which I have only been able to talk about a few. Those are the things I would like the health committee to expose," he said.
The BBC reported that Mr Walker had been threatened with legal action because of the interview.
An NHS Commissioning Board spokesman told the Daily Mail:
In relation to Mr Walker’s specific comments, we know that he is unhappy about his personal case. Allegations made by Mr Walker regarding behaviour at the SHA have been independently investigated and found to be without merit. It is important to stress that allegations of this nature are taken extremely seriously. Following Mr Walker’s initial concerns raised in 2009 Sir David commissioned a rigorous independent review, following which it was concluded that no evidence whatsoever was found of bullying and harassment by the Trust or SHA.
The former head of an NHS trust which is being investigated over high mortality rates has spoken out over patient safety concerns - in defiance of a legal gag.
Gary Walker was sacked in 2010 as chief executive of United Lincolnshire Hospitals Trust for gross professional misconduct over alleged swearing at a meeting.
He claims he was forced to quit for refusing to meet Whitehall targets for non-emergency patients and was then gagged from speaking out as part of a settlement deal.
He told BBC Radio 4's Today:
This is a culture of fear, a culture of oppression - of information that's either going to embarrass a civil servant or embarrass a minister.
These are big problems. And if you consider that the people that have been running the NHS have created that culture of fear, they need either to be held to account or new people need to be brought in to change that culture.