A senior manager has discussed a grievance amongst other things with his spouse who used to work for the company (no longer does).

We discovered this by accessing another employees emails during a grievance she had submitted to the company (she was off sick).

We believe from the email discovered that the employee has discussed the grievance with his spouse who knows the aggrieved employee and has possibly been advising her of her problem/issue with our company. Whilst the senior manager was on holiday we also accessed his emails and found emails to his spouse.

We have done an investigation – the manager has not been called in for an investigation hearing, however we have invited him to attend a disciplinary hearing. My manager would now like to dismiss the senior manager due to break down in trust.

I am worried that the senior manager may take us to an employment tribunal as the evidence would not have been discovered had the emails not been looked into in the first instance and therefore we may have broken data protection.

Technically he has breached confidentiality by discussing employees but does this warrant gross misconduct?