The claimant in Day v Health Education England was employed by the NHS Trust where he was working as a doctor but Health Education England (HEE) was responsible for organising his training. HEE placed him with a hospital and, while he was working there, he raised a number of concerns with the Trust and HEE about what he considered to be serious staffing problems affecting patient safety. He alleged these were protected disclosures and that he was subjected to detriments by HEE as a result.

The issue for the Tribunal and ultimately the Court of Appeal was his status as a "worker" in order to be able to bring the whistleblowing claim. HEE argued that as it was not the doctor's employer, he could not bring a claim against them.

It was accepted that, as regards HEE, the claimant did not fall within the general "worker" definition as he did not have a contract of employment with HEE, but he argued he was within the extended "section 43K" definition for whistleblowers. This section protects some individuals who would not otherwise be covered, in particular agency workers in relation to victimisation for whistleblowing disclosures made while working for the end user. It covers individuals who have been supplied to do work by a third person, provided the terms are not set by the workers themselves.

There were two potential problems for the claimant:

• The section 43K definition says it does not apply if the individual falls within the scope of the standard worker definition. Here the claimant did fall within the standard definition – but in relation to the Trust, not HEE.

• Did HEE substantially determine the terms on which the claimant worked so as to be an "employer" within section 43K?

The EAT decided both these questions against the claimant, preventing him from bringing his detriment claim, but the Court of Appeal has now allowed his appeal. The fact that the Trust was his employer could not prevent HEE also having that status. Section 43K must be read as allowing someone to bring a claim as long as they are not a standard worker for the employer they are claiming against. Any other interpretation would mean that an agency worker with an unrelated evening job would be prevented from making a claim.

As for who "substantially determined" the terms on which the claimant was employed, the Court said this could be both the Trust and HEE – it didn’t have to be one or the other. The case has been sent back to the Tribunal for this to be decided.