For the last few years a picture of great significance has hung on the wall above Bobby Barrett's bed in his care home just outside Glasgow.

The retired engineer and his old pal Gordon Bell are in it, dressed in his work overalls outside the Meadowside Granary building at Clydeport.

Bobby's memory isn't as good as it used to be which is why he is in the room he's in now.

Dementia is a tricky curse to have but he hasn't forgotten March 28, 1990. He certainly hasn't forgotten Gordon.

Which is why today is such a very important day.

Nearly 30 years after he and Gordon posed together for that photo, the pair are about to be reunited after a chance event got the long-lost pals in touch with each other again.

"I'm a wee bit worried I won't recognise him now," he says, as a care worker brings in a tray laden with tea and biscuits. "It's been a while."

Bobby and Gordon's reunion actually began a year earlier at the news desk of STV with a large, slightly battered book and some curious journalists.

The book, Glasgow: 24 Hours in the Life of a City, was passed around and the idea for a story had grown.

It featured images taken by 33 of the world's top photo journalists, who spent 24 hours capturing everyday life in the city.

On March 28, 1990, as the clocks struck midnight, they took up positions across the city.

One was with the driver of night bus 801 as she began her shift, picking up revellers into the wee small hours.

Another was at M&A Brown bakery as the first batch of morning rolls emerged from the ovens, while over at the Rottenrow Maternity Hospital, a particularly nervous young photographer waited for the first babies of the day to enter the world.

At Clydeport, Robert 'Bobby' Barrett and his pal Gordon Bell were preparing to start their working day.

The Glasgow Shoot project had begun. By the end of the 24-hour photo marathon the photographers had taken 40,000 images.

The result was the book that had now found its way into a newsroom nearly three decades later. The decision was made.

To mark the anniversary, STV journalists announced they were looking to track down the people who appeared in the book. Emails and phone calls flooded in.

"I didn't even know I was in the book until a few years later when my friend spotted me in it," said 46-year-old Tanya Hamilton, who still lives in Glasgow.

"I knew there was a photographer in Yorkhill that day taking my picture but I had no idea why. I left nursing a few years after the picture was taken."

"My friend just sent me a screenshot of a tweet from STV looking to find people that were featured in the book," said George Graham.

"I am the boy with the hamster! I remember the day so well. The picture of me crops up every couple of years and is such a good memory. I'm now a a kindergarten teacher in Thailand.

"Oh, and I don't have a hamster any more, the hamster in the picture actually killed itself by jumping into the class aquarium the following summer."

A man wrote in who had been pictured eating his pizza on a night bus, another phone call was from a young mother who had been the first baby photographed being born in Glasgow that day.

Among the many replies there were also several international ones - including one from a Gordon Bell in Colorado.

"My sister sent me the article and it is great seeing all the photos again," wrote Gordon. "I can't believe it has been so long."

He left Glasgow in 1996 and has been living in Colorado for the past 20 years.

"That's Bobby Barrett beside me in the photo," he said. "We've lost touch and I'm not sure where he is now but I have some great memories of that time."

Gordon was interviewed by phone and went on his way. Then, a few hours before the story was due to be published, a lady called Mrs Barrett rang up the news desk.

"My husband, Robert, is in that book, the one you're looking for people who took part in it," she said.

"He's the man on the left holding the great big spanner. Bobby is now in a care home and suffers from short term memory loss.

"He loved this photo and had it printed on a big canvas which now hangs on the wall in his room."

There are more than five million people in Scotland but out of them all, Bobby Barrett had been found.

So had Gordon Bell, albeit more than 4000 miles away.

Through STV, the pair swapped numbers. Time was important because, as Mrs Barrett said, her husband was fighting through the challenges of dementia.

A year later, the friends finally managed to reunite after nearly two decades apart.

On an afternoon at the end of April, the old pals met up at Bobby's care home.

In the old days they would have been at the pub for their usual pie and a pint but now biscuits would do fine.

As soon as Bobby's door swung open, he was met with a firm Scottish handshake from Gordon and left with a hug.

They chatted away about their old life in Glasgow, of how the Clyde shipyards have fallen silent and how the store Bobby's wife used to work in has been turned into a pound shop.

They reminisced about a time when you knew your neighbours, of life in the towering Red Road flats and shared stories about their families now grown.

Gordon gave Bobby a shirt, with the Colorado flag, and the pair have promised to stay in touch.

Both men were born in Springburn and Bobby, 73, says he can still remember the gas lamps and the 'single end' living which meant you had one room with your kitchen, bed and sofa all in the same place.

They both remember the day the photographer came to ask them to pose for him.

"The gaffer came over and said some guy wanted to take our picture so we went and looked out the biggest tools we could find," laughs Bobby, who chose a giant spanner while Gordon grabbed a hammer.

They posed, grinning in the sunshine, while the photographer took his shot and went on his way.

Richard Wait was the man holding the camera that day and he remembers the pair well.

"I had a type of camera with a large black cloth that I had to pop under to take their photograph so I was probably quite memorable, too," he says.

They had no real idea what it was for but later it appeared on postcards and in a large book which they laughed about.

As the years flew by though, time added more value to the photograph as it so often does.

As Gordon's wife Susan said after the two friends finally said goodbye: "This has touched Gordon very deeply. What may have started out as an assignment, an article, turned into something meaningful beyond words.

"The smiles in the photos tell the story."