Thanks to Samantha Cooper of Outer Temple Chambers for preparing this case summary
If, during a hearing, an employment tribunal receives information from a third party that may be prejudicial, should it disclose that information to the parties and recuse itself from hearing the matter?
Yes, held the EAT in Begraj v Heer Manak Solicitors, but not in every instance.
An Employment Judge was approached by Police Officers part way through a hearing to speak in private. The Officers provided the Employment Judge with information regarding alleged criminal activity of one of the parties. The Employment Judge acceded to the request of the Officers not to reveal this communication to the parties.
Several days of evidence later, the Employment Judge determined that it was in fact necessary to disclose the approach to the parties. The Respondent made an application for the employment tribunal to recuse itself, which it did, applying the test in Porter v Magill  2 AC 357 "whether the fair minded and informed observer, having considered the facts, would conclude that there was a real possibility that the Tribunal was biased".
Upholding the decision of the employment tribunal to recuse itself, the President noted the importance of the reality and the appearance of impartiality and provided guidance for employment tribunals in such situations at paragraph 53.