It is a fact that separates the barrister, by about 15 minutes, from the cafe customers now caught up in the siege that has put central Sydney in lockdown.

"The guy who served me ... no doubt [is] being held hostage, which is tragic," he says.

Michael says it was a relatively quiet morning when he placed his 9.22am order before lingering in the cafe for a few minutes after running into a client.

"It wasn't what I would consider to be busy," he says, noting there were about 15 to 20 people, including a cafe staff of at least four, at the time of his visit.

By contrast, he says the number of hostages could have been far higher if the situation had unfolded 24 hours earlier.

Michael says the cafe was packed with people for the weekend pre-Christmas rush on Sunday, when he stopped into his work at the building's eighth-floor Garfield Barwick Chambers.

"There was a queue out the door," he says.

"If they had gone in even at 8.30 [this morning], it would have been a lot busier because a lot of people get their stuff before they go to 9 o'clock work."