We are often led to believe that the high performer is untouchable, so you need to clarify this first. Does leadership actually believe this person is irreplaceable? When you map out who actually carries the knowledge and brings in that revenue, the answer is usually not as clear cut as leadership believe. There are very few high performers who do not have a team around them doing the heavy lifting. That is worth establishing before you do anything else.

The next step is for you to decide what your actual goal is. Do you want to retrain the employee, put them on a PIP, or manage an exit? What is your end goal? The strategy looks completely different depending on which one you are working toward. If you have not named that clearly, you will keep circling without landing anywhere.

Now, the business case. Stop talking about morale and start talking about money, and know your audience. Is turnover in that person's team a problem and can it be linked back to that individual? What are sick leave patterns like? Recruitment costs for roles that keep turning over are a major expense. How much time have you and other managers spent managing the fallout from this individual? A high performer who drives out three good people a year is not the asset leadership thinks they are. They just look like one because nobody has looked at the other side of the ledger. And that is before you count the customers they have damaged, the deals they have lost, or the reputation they have quietly been burning through.

My biggest piece of advice is do not let this look personal. I have seen HR people make this mistake more times than I can count. It becomes a crusade, and the moment it does, management stop listening. Not because they think you are wrong, but because they decide you do not understand the business. Step away from culture and morale. Those arguments will not land with a leadership team under commercial pressure. Make it hard facts about business impact. You are not building a case against an individual. Make it about what this is costing the organisation in real terms, and keep it there.

If you want to succeed, you need backers. Think about who else in leadership sees what you see. If the person doing the protecting is the CEO or MD, going back to them alone with the same argument will not change anything. When multiple voices are saying the same thing it stops being an HR concern and becomes a business problem that cannot be ignored. The CEO can ignore you, but they cannot ignore it when several people are saying the same thing. Do not bring this to leadership until you know you will have the backing. This is often a step that HR people miss. Do the groundwork before you go into that meeting. Someone told me years ago, do not ever go into a meeting with a proposal unless you already know you have the votes.

Put the legal risk in writing. If people are leaving because of this person's behaviour you are looking at constructive dismissal exposure. If complaints have been raised and not acted on, vicarious liability is a real consideration. Say it clearly and make sure there is a record that you said it.

On training. If leadership is reaching for it as an alternative to accountability, push back. It can work, and a well facilitated session on leadership impact or psychological safety can sometimes land a message collectively that a direct conversation cannot. But it will not fix behaviour that has never faced a real consequence.

This is not about the individual. It is about what the organisation is choosing to tolerate and what that tells everyone else on the team. I have sat in rooms where this conversation felt impossible, where the easier option was to file it away and hope things improved by themselves. They rarely do. What happens if nothing changes? Your best people leave quietly, your middle performers disengage, and the ones who stay learn that results matter more than how you treat people. That is the culture you are left with. You already know what needs to happen. Bring the data, make sure you have backers, outline the legal risk. This will not resolve itself. The only variable is how much damage is done before someone decides enough is enough. Make sure that person is you.