In they file, some bespectacled, some wearing socks pulled up to their knees, others in St Mirren or Partick Thistle kits, many of them pushing well into their 60s and 70s.

Each one has a story to tell. Some could talk of setbacks, illness, bereavement, or even indolence as working life gives way to a retirement characterised by marathon bouts in front of the television. The personal stories are all particular. There is another which is a recurring theme. A reticence when the words 'walking football' were first uttered in their presence; a veritable recoiling at the very notion. 'Naw, not for me,' they had said. 'I've played football, real football'.

And then they tried the very thing they had baulked at. They found it wasn't so different after all, that it was fundamentally the same game: passing, scoring, the odd argument over a refereeing decision and, yes, even a little running.

More crucially, it took them out of the house for an hour of companionship, 60 minutes away from a trudge around Sainsbury's with the wife but still with the reward of a cup of tea and a biscuit at the end of it.

Each week, 14 walking football sessions take place all over Glasgow from Glasgow Green to Drumchapel. That figure is the tip of the iceberg. Across Scotland, more than 100 similar groups meet regularly. There's even a national league where Hearts are the three-time reigning champions, and a Scottish Cup for over-50s and one for over-60s won respectively by Raith Rovers and Kirkcaldy in 2019. Motherwell, Ayr United and Linlithgow Rose are also among the regular challengers for trophies.

“To celebrate EURO 2020 we've got an over-50s league at Toryglen with 12 teams who have come from all over Scotland,” says Matt Ramsay, Glasgow Sport's football participation officer and a trustee of Walking Football Scotland. “A team is representing Baku, a team is representing Munich, they're not representing their own team but one of the host cities. After two months of fixtures, Glasgow tops the league.”

There's also an over-70s competition planned for this season and Ramsay is scouting for players. One man named Alec, who plays at the Glasgow Club in Bellahouston Leisure Centre, has caught his eye. Ramsay asks if he would be free to play.

“Is there an over-75s?” asks Alec mischievously and Ramsay is wrong-footed in the way a harassed left-back might have been sidestepped by a prime Jinky Johnstone.

“Over 75s. What age are you?” says a clearly shocked Ramsay, who promptly learns that Alec is 79.

Earlier Alec had danced about the court in the manner of Fred Astaire in steel toe caps. More than once there is the clatter into the back of an unwitting opponent and then the ball is deftly nicked away.

I know this because I feel the full force of it, having asked to make up the numbers in a game. There is a mistake in thinking 60- and 70-somethings will tread lightly. On the contrary, shorn of the stereotypical image of pipe and slippers, bounding about, reliving lost youths, they are a fearsome prospect.

If there is a danger in underestimating the elderly, there is a similar naivety in dismissing walking football as the preserve of the all-but infirm. I leave the pitch drenched in sweat. The game is quick, sharp and frenetic. You have three touches, meaning your first must be velcro-like, you can't tackle but people do, there's an extended penalty area because, wait for it, professional fouls have become an increasing problem. In short, the combatants want to win. I hear a story of one walking football game involving a Celtic team and a Rangers team that had to be abandoned for fear that it was going to turn violent.

As the name of the game suggests you can't run (three strikes and it's a penalty), although more than once I see passing resemblances to the walking event at an Olympics, you know those races in which competitors look as if it's opening day at the Black Friday sale?

On the whole, though, this is a game championing fun, friendship and camaraderie, of recapturing the spirit of the dressing room and enjoying the chance to improve both mental and physical health. A card is being passed around for a team-mate who has just lost his wife. Support at times of bereavement is a recurring theme and Ramsay tells me of one group where a number of men came to a funeral to pay their respects.

“I was quite overwhelmed by it,” he says. “I think the family was just blown away by the support from guys who just turn up and play football. And they maybe didn't know him that well but from his point of view that was a massive show of support to arrive on the day and see these walking footballers standing there with him.”

The universal truism here is that all of the players have tales to tell, some much more so than others, but football is the great leveller.

“These guys are out of the house more and they're taking part,” says Ramsay. “The knock on effect is that they are going to the doctors less because they are healthier and fitter and not just from the physical health benefits but the mental health benefits. These guys have a purpose, something to do, they're getting a chance to speak to people. The camaraderie – you couldn't put a price on that – and the social benefits of that are massive.”

Bobby still helps out as goalkeeper coach at Renfrew Juniors, where he once played and says he can't wait for Tuesdays and Fridays to come around.

“I retired last June and was watching television for 12 hours a day,” says the 70-year-old. “I love it, it keeps my mind operating, rather than sitting watching the TV.”

Meanwhile, Alan, 62, first started coming to walking football a few years after he had been diagnosed with leukaemia. It gave him a purpose, a chance to keep his fitness up. A former Junior player with Benburb and Johnstone Burgh, he is atypical of those present and bears witness to the success of the programme at the Glasgow Club in Bellahouston.

Six weeks earlier he had just had the second of two knee replacement operations, a day earlier he had been told the leukaemia was gone for good. He bristles at the idea that walking football should be dismissed with the wave of a hand despite having previously been of the same opinion.

“About a year and a half after being diagnosed with leukaemia I started thinking I needed something to do and someone told me about the walking football. I thought 'walking football? It's not for me, I've played too much football'. Once you get into it you don't realise how physical it is – not physically hard – but I come off the park sweating buckets. It takes your mind away from things, gets you away from it for an hour.”

“There was an ad for Halifax about five years ago and it was old guys setting up a walking football team and they were hardly moving. That's what people think when you say you play walking football, they think back to that advert. When I tell people to try it they'll say 'och, that's not for me' but I'll just say 'try it'.”

For more information on walking football contact walkingfootballscotland.org