A radiographer who blew the whistle on NHS malpractice is to challenge the non-disclosure agreement (NDA) she was asked to sign, in a hearing which could have major implications for the future of gagging orders.

In 2012, Sue Allison, 57, reported a string of missed cancer diagnoses and wider concerns about standards of care in a breast screening unit at Morecambe Bay NHS Foundation Trust.

After raising concerns with a colleague, the pair claimed they were ostracised and subjected to extensive bullying, eventually leading them to file formal grievance complaints against the trust.

But in 2015, Mrs Allison claims she was pressured into signing two non-disclosure agreements (NDAs) without legal advice, preventing her from publicly airing her concerns or bringing future claims against the trust.

At a hearing at Manchester Employment Tribunal on April 2, her lawyer will now argue it was unlawful to ask her to sign an agreement without legal representation, and will press for it to be revoked.

Mrs Allison claims she did not fully understand what she was agreeing to, arguing she was “pretty much conned into signing” the NDAs.

She told The Telegraph “When you’re a whistleblower and they’ve been trying to squash you for a couple of years, you find yourself in a very lonely place where you don’t have anyone to help or advise you.