An employee who is dismissed shall 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 performed (or proposed to perform) any functions as such a representative or a member of such a committee,
he brought to his employer's attention, by reasonable means, circumstances connected with his work which he reasonably believed were harmful or potentially harmful to health or safety,
For the purposes of subsection (1)(e) whether steps which an employee took (or proposed to take) were appropriate is to be judged by reference to all the circumstances including, in particular, his knowledge and the facilities and advice available to him at the time.
Where the reason (or, if more than one, the principal reason) for the dismissal of an employee is that specified in subsection (1)(e), he shall not be regarded as unfairly dismissed if the employer shows that it was (or would have been) so negligent for the employee to take the steps which he took (or proposed to take) that a reasonable employer might have dismissed him for taking (or proposing to take) them.