She looked up to see a ''solid'' man of average height coming round the counter towards them.
Thomson said she was puzzled as to what was happening until she noticed he was wielding a tyre iron, and wearing a hoodie and scarf, obscuring his face.
''You never know how you'll react until it actually happens, I suppose, but I became quite determined not to give him anything.''
She said the would-be robber stood over her. All she could see were his eyes. ''He seemed quite calm at this stage, and just kept repeating, 'Smokes and money . . . smokes and money'.''
When she stood her ground, the man became threatening.
''He smashed the pie warmer with his tyre iron, and had a go at the till, too, but I wasn't going to give him anything.
''I was thinking, 'Bugger off, I've worked too hard for you to come and steal it'.''
While the incident was unfolding, other customers had come into the dairy, and then left to alert the police.
Thwarted by Thomson's determination, the man ran from the store and made for his car.
He was seen leaving by another customer, who noted the vehicle's details.
Police apprehended a 20-year-old Dunedin man shortly afterwards. He was due to appear in the Dunedin District Court on charges of aggravated robbery.
Reflecting on the incident yesterday, Thomson said she was not sure if she would act with such courage again.
It was the first such incident in her six years running the dairy.
''I always tell staff, if it ever happens, just give them what they want.
''To be honest, I just hope there never is another time.''
She said she had been heartened by ''dozens'' of messages of support since Tuesday.
''The way it all worked out just shows what a great wee community this is.''
The store reopens today.