"There are loads of people in London, but it can feel like a lonely place," explains Kieran Duff on the stroll through Russell Square, still stewing on the fact he has forgotten his football socks for the big game. "Hopefully someone has a spare pair."

In the changing rooms, a welcoming, ready-made friendship group of Newcastle-supporting team-mates pull on black and white jerseys while musing about early season defeats by Juventus and Inter Milan. No one brought extra socks.

"It feels silly to say, but it does feel different playing in the kit and colours," says Newcastle Supporters' Club captain Tom King.

"There is a little bit of your brain that is like 'I am playing for Newcastle here'. It makes you connect with the club in a way I haven't with any other football club I have played for."

Next door, lads in vintage claret and blue begin to trot out and warm up. It's a pleasantly mild Sunday lunchtime in November as Newcastle take on their Aston Villa counterparts at Coram's Field in central London, the final embers of autumn clinging on as a groundsman attempts to clear leaves off the pitch.

This is just the start of a bumper afternoon of London Supporters' League action that also includes AC Milan, Fiorentina, Genoa and Lazio, but on any given weekend you can find Paris St-Germain, Real Madrid, Lyon, Roma, Monza or Panathinaikos here. All dressed head to toe in full club colours.

"We won the league last year, after eight years we finally managed to win it, so we put a star on top of our crest," beams Ludo Romagnoli, who was born in Modena before moving to Brazil and then came to London for university. "I feel so much pride representing our club."

"It is more fun to face people who feel the badge, the colours, and have that passion for the club they are representing," adds Pedro Aguilar, from Real Madrid London.

"Everyone has a story behind them - you get to understand why they support the team, why they love it.

"That is fascinating. Meeting people from different backgrounds and cultures and seeing how much they love football, just as we do, just through a different team."

In fact, it really began with one man just wanting to watch his football club.

Massimiliano Ciccone was a Lazio season-ticket holder before leaving Rome in 1998. "Two years later, Lazio won the league for the first time in almost 30 years," he laughs.

Yet when he arrived in London in 2013, it was difficult to find somewhere to watch Lazio games - once he finally sourced a venue, more and more fans joined him.

"I realised we were not alone, there were a lot of people with a reality like us, who in their own country followed their team very closely, some ultras, going home and away, or being passionate about it," he explains.

"Then they move abroad and kind of lose this link with their team and try to recreate it where they are, by gathering with people who support the same team."

When Ciccone's group, the Lazio London Casuals, became friendly with supporters from an AS Roma UK club, they suggested playing a derby match.

"I have to be honest, I was a bit worried about it, you don't know what to expect," admits Ciccone. "It was heated but nothing resulted in fights. So we thought 'that was a good experiment. Why don't we keep doing it every year?'"

As word spread, the London Supporters' League was born. Now playing its ninth edition, the eight-a-side competition has grown to 14 teams. Ciccone would love to expand, and has requests from other fan groups, but is limited by pitch availability.

The league also decided not to allow London teams, with the idea being it provides space for fans not originally from the city to meet and enjoy their football club.

They vet new clubs to make sure they are legitimate supporters, and Ciccone makes sure not to schedule teams to play at the same time their 'real' clubs are in action.

They gather stats - goalscorers, best goalkeeper, man of the match - each game and host end-of-season award ceremonies.

"I feel like a little version of [Fifa president Gianni] Infantino, you need to make everybody happy!" he laughs.

"It is kind of a social experiment, because I have noticed over the years that initially the players were more prone to little altercations, because they were all new and there was 'you support this team, I support my team'.

"Now they play and meet each other regularly, they have become kind of friends. That's a good thing! It's a nice tournament and I love it. It's fun, the spirit of it."

The real success has been the opportunity the league provides for players to meet fans with a shared identity and belonging. A "common passion" as Newcastle captain King describes it.

He was just looking to get back to playing football after the Covid pandemic and stumbled across the Newcastle United Supporters' Club London as a result, the London Mags as they are also known.

The wider fan group has been going for 60 years and boasts 500 members. As well as football they play darts, golf and pool, though one fan jokes you're more likely to face Plymouth and Exeter than Real Madrid or PSG in the supporters' pool league.

They host pub quizzes, Christmas dinners and various other events. Some travel to away days together, attend each other's weddings and become lifelong friends.

"It helped me connect to my roots," explains King. "You go to London and it can be quite a lonely place, especially when you don't have a pre-existing group.

"Finding all the lads and forming real friendships is really nice. It's a good group who look after each other, you have that common bond of being from the north east, having the same outlook on life."

That sense of building a community is perhaps only heightened when moving from abroad, as Milan captain Romagnoli explains: "When I moved here and found out about the club, it changed my life, because I had people from all over the world really that had the same passion."

Real Madrid, meanwhile, boast a truly global feel to their team.

"We have players from South Africa, India, Colombia, Ecuador, Romania, one guy from the UK, Spain obviously, and our goalkeeper is from Albania," says Aguilar, who grew up in Venezuela supporting Los Blancos.

"It is amazing how we are bonding over a love for Real Madrid. We do barbecues and celebrate birthdays together - that is the whole point of why we started.

"It gives people an opportunity to have that sense of belonging, through football, through Real Madrid, make some friends and grow a nice community."

Villa edge past Newcastle 2-1 in a tight tussle between the only English sides in the league.

"We had a good side out," says Villa supporter Lloyd Perry, who travelled more than an hour across London to watch his team-mates. "Everyone wanted to face the Geordies!"

After a pitchside post-match debrief, both sets of players wander to The Dolphin Pub, a regular haunt for the London Mags.

"It's nice there are a group of lads in a similar position to you," says King of the friendship between teams. "There's that sense of camaraderie between us."

Back at the pub, a huddle of players dissect where the tactical battles were won and lost, before the women's Tyne-Wear derby kicks off on the big screen.

Those in black and white passionately celebrate each Newcastle goal like they're on the terraces at St James' Park. The transformation from player back to fan complete. Until next Sunday, that is.