In Henderson v General Municipal and Boilermakers Union, Henderson (H) was employed as a regional organiser which involved undertaking political work as part of the region's political efforts on behalf of the Labour party. H believes in “left wing democratic socialism”. H argued that he had been dismissed because of his philosophical belief and also that he had suffered harassment related to his belief.

H’s dismissal followed the raising a grievance, part of which was that “extreme right wing elements in both the GMB and the Labour party have colluded to prevent a left wing unionist and a Labour party activist from a working class background making genuine progress in our movement.” The harassment claim related to the GMB general secretary saying that H was too left wing after Ed Miliband allegedly expressed his displeasure about H telling the media that Labour MPs should not cross a picket line.

First, the Tribunal decided that left wing democratic socialism is a philosophical belief for the purposes of the Equality Act 2010. This provides a further example of how wide an interpretation is being given to this protected characteristic. The Tribunal then found that a large part of the reason for H’s dismissal was because of his belief, i.e. that is was the effective cause. A hypothetical comparator who held a different belief, or no belief, would not have been treated in the same way. Also, H’s treatment by the GMB general secretary was harassment as the conduct related to H’s belief and it had the purpose of creating an intimidating, hostile or humiliating environment for him.