I was invited to see The Australian Ballet perform Verve at the Sydney Opera House, and I arranged to meet my friend at the box office at 6.30pm to collect our tickets before the show.

She called me about midday and asked me what I was wearing.

“I have to go straight from the office,” she said.

“I’m wearing a pantsuit and heels. Do you think that’s okay?”

My friend normally wears tailored navy pantsuits, by Carla Zampatti, or Armani, so I was sure she looked more than presentable.

“I’m wearing a cream silk and lace high necked blouse and black silk pants, and I have gold high heeled sandals in my bag to change into,” I assured her. “We’ll be fine.”

We arrived at the Opera House and in the queue for a glass of wine, my friend checked out the crowd.

“Everybody looks so casual” she said, horrified.

The dress code for going to the theatre, ballet or opera has shifted dramatically. Photo: Getty

She’s from Melbourne. I looked around unconcernedly, as I am now immune to it. It used to bother me, Sydney’s lack of sartorial effort, but now I’m just thrilled if people are wearing shoes.

“The crowd in Melbourne really dress up for the ballet, especially if it’s opening night,” said my friend, staring at someone’s frayed jeans in front of us.

“The men will wear a suit, the women are often in formal dresses, and cocktail coats.”

I sighed. Imagine that! What if, think about it, women wore actual opera coats, which is what those beautiful silk satin or brocade coats are literally called. Opera length gloves. Jewels. What if they had their hair done?

Opera gloves and pearls were once a staple attire. Photo: Getty

What if a person thought, I’m going to the Opera House tonight, I think I’ll dress up? Hell no, not in Sydney.

It was all T-shirts, and leggings and leathers jackets and whatever was at the end of the bed that morning.

I did spy one woman in a chic, tightly belted long black coat, but I knew her and she works at a fashion magazine, so that doesn’t count.

Back at the bar during interval, my friend suddenly dug her nails into my arm: “That girl doesn’t have any shoes on.”

I spun around and looked at the young woman in the line next to me.

It had finally happened. She had bare feet. “Maybe she left them under her seat?” I whispered hopefully. My friend was losing it.

“Look,” she said, pulling out her iPhone.

“This is a shot of my mother and sister at the opening of Cinderella in Melbourne.”

Her mother and sister were in beautiful long dresses. The sister was wearing a black satin cape and pearls. They were both wearing shoes.

After the performance my friend and I were invited into the green room to toast the wonderful corps who are all off to dance in New York.

Given that they had just danced their hearts out for two and a half hours I was expecting them, rightfully so, to be in trackies and singlets, but no, one beautiful girl was in a grey belted Karen Walker pantsuit, while another male dancer was wearing a fabulous 50s-style green jacket with a white shirt and smart tailored trousers.

Ah, Sydney. All the elegance was backstage.