Image copyright Chris Stead/Courtesy Stephen Mills Image caption Stephen Mills (centre) with the safe he had just opened

A Canadian man unlocked a safe that had sat unopened in a small museum for decades, cracking the code on his first try with a lucky guess.

Stephen Mills was visiting the Vermilion Heritage Museum with his family when he had a go at opening the iron box "for a laugh".

The museum in the province of Alberta had previously tried numerous times to unlock the old safe - to no avail.

The safe had not been opened since the late 1970s.

The museum, housed in an old brick school building, hosts a collection on the history of Vermilion, a town of just over 4,000 people.

Mr Mills, from Fort McMurray, Alberta, was visiting Vermilion with his extended family during a long weekend in May.

"When we go camping every summer, we've come to learn that every small town, no matter where you go, has something to offer," he told the BBC.

So the family brought the children to see the museum and was given a tour by volunteer Tom Kibblewhite.

One of the exhibits was a safe that had originally been in the town's Brunswick Hotel, which had opened in 1906.

The safe itself is believed to have been bought in 1907.

It was donated to the museum in the early 1990s after the hotel changed ownership and was renovated.

Mr Mills said when they were shown the safe, the whole family "was intrigued".

How did he do it?

The museum had previously enlisted the help of experts to crack the code, tried default combinations, and had contacted former hotel employees to see if they could help.

Like the Mills family, other museum visitors played around with trying to open it, with no success.

You may also like:

"I said to [Mr Kibblewhite]: 'that's a crazy time capsule. You don't even know what's in it,'" said Mr Mills, who works as a welder.

He noticed the dial numbers ran from zero to 60, and decided to try 20-40-60.

"Typical combination lock, three times clockwise - 20 - two times counterclockwise - 40 - once clockwise - 60, tried the handle and it went," he said.

"I could tell it wasn't opened for a long time because some dust fell out from the locking mechanism."

Mr Kibblewhite told the BBC "it was a thrill" when he turned and saw the door swinging open.

So what was in the safe?

Sadly no treasure. It contained an old pay sheet and part of a restaurant order pad, dating from the late 1970s.

The pad included receipts for a mushroom burger for C$1.50 ($1.12; £0.59) and a package of cigarettes for C$1.00.

"They have no value really, but they are of great interest to us. It gives us a little bit of idea of what the places were like in 1977, '78," said Mr Kibblewhite.

What are the chances?

The odds of Mr Mills correctly guessing the combination are pretty long, says the University of Toronto's Jeffrey Rosenthal, author of Knock on Wood: Luck, Chance, and the Meaning of Everything.

He calculated the chance of correctly guessing the combination on one try as 1 in 216,000. (His calculation assumed the safe numbers actually ran from one to 60).

But he noted that some combination locks allow for wiggle-room and if this one had a three-digit leeway, Mr Rosenthal put the chances at 1 in 8,000, "which is still a small chance".

The fact that the combination was in a specific pattern and did not appear to be a random combination of numbers could also factor into a calculation of the odds, he added.