A London law firm has lost an appeal of a ruling that it discriminated against a gay barrister.

In a memo discovered by Lee Bennett in firm archives in 2010, a partner at Bivonas LLP had written that he should be sacked and that he would “take our cases to his batty boy mate”.

The Employment Appeal Tribunal agreed with the original ruling that the content of the memo was “a professional slur of the utmost gravity”.

The law firm had claimed the note, written in 2008, was a “personal aide-memoire”, not intended to be kept or showed to anyone.

It lost its argument on appeal that the Employment Tribunal was wrong to say that the insult was a detriment.

The Employment Appeal Tribunal found no evidence that any straight men had been insulted in the same way as Mr Bennett for being gay.

The firm could not provide justification for treating Mr Bennett differently to other employees.

The Equality and Human Rights Commission funded Mr Bennett’s defence against the law firm’s appeal.

John Wadham, Group Director Legal, Equality and Human Rights Commission said: “Homophobia will not be tolerated in the workplace or anywhere else. We funded Mr Bennett’s defence and this win has set a precedent for discrimination law.”

Bivonas said it had “the appropriate measures in the light of the Tribunal’s observations”.