A thank you to all the quiet heroes keeping us safe this Christmas.

My friend’s husband had to go away for work yesterday. He didn’t tell her where he was going. He didn’t tell her when he would be back. He never does.

Three days before Christmas, my friend was mentally adjusting her plans for this weekend if she and her two kids had to do it without Dad.

“But, surely, he’ll be home for Christmas Day?” I’m asking, over wine and spaghetti at dinner last night.

“I don’t know. No idea.” She isn’t angry about it. She isn’t surprised.

My friend’s husband is in the Federal Police. Today, seven men were arrested in Melbourne, suspected of planning a significant terrorist attack in Melbourne‘s city centre this weekend.

Victoria Police Chief Commissioner Graham Ashton stood before a press conference today and told the media that these men had planned to use explosives and knives cause chaos and carnage “on or around Christmas Day”.

It’s alleged these men were planning to kill and injure men and women and children who had gathered in the city. Think about that. On Christmas Eve, there’s a family concert at Federation Square. There’s midnight mass at St Paul’s Cathederal. There are tourists milling, families travelling to be together, friends meeting on the steps of Flinders Street station. There’s Carols By Candlelight.

Until today, I hadn't thought about my safety this Christmas. I hadn't thought twice about the picnic I'll be having at the beach on Christmas morning. I hadn't considered whether my family would be safe when we crossed the city to visit our in-laws for lunch. I hadn't second-guessed whether it will be safe to take my children to the fireworks on New Year's Eve.

I hadn't been thinking about that. But my friend's husband had. He, and all the other men and women who work for the Federal Police, the State Police, the emergency services, have to think about this constantly. It's their job.

I'm wondering whether my children's present piles are even, and if there's enough champagne in the fridge. I'm making a list of the last-minute stocking fillers I have to buy tomorrow, and fretting about how long the queues will be for the ham.

Those people are putting plans in place for how to evacuate and limit loss of life if the worst happens. And, most urgently, how to stop the worst from happening.

They are travelling away from their families while we are travelling towards our own.

They are working through the night while we're wrapping presents and drinking and singing and gasping at fireworks.

Because my friend's husband is away from her today, the rest of us can worry about the price of prawns.

It's a remarkable thing to do for a living. Thank you so much for doing it for us. Today, on Christmas Day. Every day.

Just, thank you.