Eton College has upheld its decision to fire a teacher over a lecture which defended male aggression as a biological fact.
English master Will Knowland was sacked after posting a lecture he had been told not to give on YouTube.
His video, entitled Patriarchy Paradox, breached Eton's legal obligations, the school said.
Mr Knowland has raised more than £60,000 to challenge the decision at an employment tribunal.
The lecture suggested that "saying smash the patriarchy amounts to saying smash human nature and biological reality".
In a letter posted on Twitter, Mr Knowland said he was fired because of the video, and called an instruction by the school to remove it "censorious".
Another teacher, Dr Luke Martin, subsequently resigned as head of the perspectives course at the school.
In his resignation letter he wrote: "The point of perspectives is that boys are exposed to various perspectives, some of which they will disagree with."
In a statement the school said: "Eton can confirm that the appeal panel has upheld the decision to dismiss Mr Knowland."
It previously said it was advised by lawyers that the video was problematic.
It said it made a "reasonable request" for him to take it down, "but despite multiple requests and then instructions he persistently refused to do so".
It added: "We are always saddened to see matters reach such an outcome but the school had no choice in the face of clear legal advice and the persistent refusal to remove the content."
An internal disciplinary process determined Mr Knowland's actions represented gross misconduct.
The Duke of Cambridge and the Duke of Sussex were pupils at Eton College, which charges more than £40,000 a year.
Conservative prime ministers David Cameron and Boris Johnson are also among its alumni.