An employee who is dismissed is to be regarded for the purposes of this Part as unfairly dismissed if the reason (or, if more than one, the principal reason) for the dismissal is that the employee—
made (or proposed to make) a section 63D application,
exercised (or proposed to exercise) a right conferred on the employee under section 63F,
brought proceedings against the employer under section 63I, or
alleged the existence of any circumstance which would constitute a ground for bringing such proceedings.