When BBQ King announced its shock closure on Thursday, Sydney lost more than a restaurant.

The bombshell news reverberated through the close-knit culinary community, already reeling from the COVID-19 pandemic that is decimating the hospitality sector.

Celebrity chefs were among those lining up to mourn BBQ King's loss and pay tribute to its 40-year legacy that helped shape the city's food culture. The Chinatown eatery was more than the sum of its hanging ducks in the shopfront. It was an institution, a nod to all things good about Sydney's multicultural dining scene.

Celebrity chef Neil Perry said he found the news "hard to believe". He has fond memories of visiting BBQ King with his father in the restaurant's early days and later developed a friendship with owners Philip and Agnes Chau.

"It's just really sad because I love those guys. I've known them a big chunk of my life," Perry said. "You always ordered the same thing and it was always delicious."

The eatery's popularity was multi-layered and to properly understand the reaction to BBQ King's closure is to realise the unique place it occupied in Sydney's food scene.

It wasn't just another Cantonese restaurant selling roast duck and pork. It accumulated a cult following because of its lengthy opening hours (pre-lockout laws when late nights were still allowed).

And BBQ King served those who served. It was where chefs and hospitality staff went to unwind late into the night after working themselves into the ground feeding their own customers.

"It will always have a solid place in the heart for people of my generation in restaurants," Perry said. "We love it when we're working hard and looking after so many people, [then] being able to go to a place [ourselves]."

Billy Wong's family owns Golden Century, one of BBQ King's long-standing Chinatown rivals. Except he doesn't see it that way.

"I don't think we ever saw each other as competitors. They added a dimension to Chinatown and were part of the offering. Our families have always known each other as well," he said.

"BBQ King has been a late-night haunt for many chefs and people who have been out [late]. For them to close, it's the end of a chapter for BBQ King but it's sad to see. It's a bit of a shock. I wish them well."

Neither Perry nor Wong were sure whether the closure was due to financial reasons related to the pandemic, or simply because the couple decided to call it a night and retire.

Cecilia Chau, the daughter of BBQ King's owners, declined The Sydney Morning Herald's requests for the family to comment.

The family has always kept a low profile, although Philip Chau made headlines in 2003 after he endured a dramatic three-day kidnapping ordeal. His five captors – who were later jailed – bound, beat and starved Chau until a $600,000 ransom was paid.

It's not just the restaurant community who will miss the institution. BBQ King's farewell post on social media was met with hundreds of comments from customers mourning the loss and sharing anecdotes of good times spent over Peking duck.

The Herald's chief restaurant critic Terry Durack said he wasn't surprised to hear the restaurant had shut, because "any business that was just hanging in there has been pushed over the edge by the current situation".

Durack said "the real shock" came when the restaurant moved from its Goulburn Street premises down the road to Liverpool Street in 2016.

"That seemed like the end of an era ... a little bit of Sydney's heart curled up and died when that happened."

BBQ King's Liverpool Street building sold last year to private investors for $22 million, although it is not known whether that affected the restaurant's closure.

Whatever the reason for BBQ King's demise, it comes at a critical juncture for a hospitality industry peering ahead into a grim future.

Perry is adamant that it won't be the last restaurant whose doors will never open again.

"Consumer confidence has dropped terribly," he said. "If we don't lose 25 per cent of the restaurants we had in March 2019 across the country, we'll be very lucky. We'll have dodged a bullet."