Angus McCormack is a former school captain at Girton Grammar School, an exclusive private school in Bendigo which charges parents more than $11,000 a year in fees.

He and his father, who sat on the school's board, were headed to the school's annual Foundation Day Service on the May 6.

The service was held in the nearby Sacred Heart Cathedral, and celebrated the school's 130th anniversary.

Mr McCormack, a 20-year-old fashion student at RMIT University, said the school had specifically requested he "wear appropriate attire".

He decided to "tone down my appearance and be respectful to their wishes" – ruling out an original plan to wear a dress and "killer" heels, he wrote in a Facebook post that has since been shared 4500 times.

"Therefore, I decided to wear minimal makeup, a single small earring, neat black leather pants, a white shirt with a black bow tie and black designer jacket.

"A suit by any definition of the word, although not in the typical commercial fabrics."

But Mr McCormack said upon arrival at the cathedral, he was approached by a staff member who told him he was inappropriately dressed and asked him to leave the event.

Mr McCormack  said he didn't want to make a scene and so left with his father by his side, but later wrote he felt a deep sense of embarrassment and shame about the incident.

His father  resigned from his position on the school's board soon after.

Mr McCormack told Fairfax Media he was touched his father had also left the event to support him.

"My parents are both incredibly supportive of me and who I am and everything I stand for," he said.

"So that was really amazing, it brought a tear to my eye as I got in the car and drove off with Dad."

Mr McCormack, a budding fashion designer said he felt he was discriminated against.

"It cut me quite deep. I'm usually very confident, very outgoing and it's really affected me," he said.

"My confidence has been really shaken."

Since Mr McCormack posted his story on Thursday night, his post has been widely shared, with more than  14,000 'likes' and 4000 comments on the post.

He said he wants the school to recognise their actions were hurtful.

"I want to stand up for everyone out there, children and young people who don't know who they are and might not feel accepted by their school because I think it's really important that people should be able to wear what they want and be who they are," he said.

The budding fashion designer struggled in primary school and high school before he came out as gay at the end of year 11.

He said he "is not out to get the school in any way, shape or form".

"I have great memories of the school, I had a wonderful time there - a really great education.

"I was just a little disappointed, a little hurt that they decided to single me out at this particular event." 

Angus's 'inappropriate' clothing Photo: Facebook

But headmaster Matthew Maruff has defended the decision and said the young man was turned away from the Foundation Day Celebration because he was inappropriately dressed.

"The issue is what someone wears at the appropriate time and appropriate place," Mr Maruff said.

"It's just regrettable, it really is."

Mr Maruff denied the incident was about anything other than the young man's attire, describing allegations Mr McCormack was discriminated against for his sexuality as "outrageous".

He said Mr McCormack was turned away from the event because he had not adhered to the dress code.

"It is about context," Mr Maruff said.

Though he did not see Mr McCormack on the night, and therefore could not comment on what he wore, Mr Maruff said he was made aware it was inappropriate for a person seated in the VIP section at the event.

"What we would call lounge suit would be the appropriate attire," Mr Maruff said.

He said Mr McCormack  would have known what he was expected to wear because it was consistent with the school's core values.

"It is upsetting, but we can't alter those core values for one person," Mr Maruff said.

He said he was keen to make amends with Mr McCormack  and his family over a cup of tea and a discussion to "make sense of it together".

Mr Maruff said he was responsible for making Mr McCormack school captain in 2013.

"We really do celebrate diversity and whilst from my point of view this is very regrettable and really sad – that's a pretty strong endorsement," he said.

"I am very proud of the school – my job is to build trust.

"I want people to understand these issues are complex."

- with Allison Worrall