The butt of much public mockery when Sky’s cameras captured assorted well-heeled corporate clients peering through its walls of two‑way glass last Monday night, Manchester City’s Tunnel Club is the most amusing but not necessarily most interesting renovation to have been undertaken at the Etihad Stadium during the close season. Moving on from the well fed and watered supporters staring in slack-jawed wonder at the exhibits as they prepared for battle, the cameras also gave us a glimpse of an inner sanctum that, for the time being at least, remains closed to prying eyes on match days.

The stadium’s home dressing room is as opulent as you might expect for such a wealthy club, but it is its sheer roundness that is most striking. Returning for his early plunge in the state-of-the-art hydrotherapy pool after being sent off on his home debut, Kyle Walker will no doubt have been struck by the rotational symmetry of his surroundings as he angrily flung his shin pads into one of the corners that aren’t there, before being enveloped in the life-affirming chi that feng shui experts tell us a 360-degree dwelling space provides.

Harmonising his players with their surroundings may not have been uppermost in Pep Guardiola’s mind when he signed off on the summer redesign of the home dressing room, but the decision to make it circular was a very conscious one. Much like the knights who convened around the famous table of Arthurian legend, all men who sit in Guardiola’s similarly shaped sanctuary enjoy equal status and the Spaniard is understood to have encouraged the design as a way of discouraging that most pernicious and malign of influences on team morale: the dressing room clique.

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Far from exclusive to football and regularly held up as one of the root causes for the poor performances of sports teams who fail to live up to the sum of their parts, these exclusive close-knit groups within groups are the bane of managers whose desperation to eliminate them in the interests of team or squad harmony occasionally extends to actually fretting over meal-time seating arrangements for grown adults like a bride and groom meticulously plotting to minimise the potential for internecine strife at their wedding reception.

England’s football squad has long been renowned for its cliquishness and as the players gather for the first international break of the season, we can only speculate as to how damaging division among the ranks has been for morale in a national team that has consistently come up short since 1990. It would be naive to assume more inclusive England squads might have enjoyed greater success at international tournaments, or to imagine more successful teams – hello France, Germany and Spain – have not also been adversely affected by internal divides. For all that, the ease with which England habitually qualify for major tournaments compared with the horror show that invariably unfolds once the players have been confined to barracks for five or six weeks does little to dispel the notion that the more time they spend cloistered together, the less cohesive their performances tend to be.

Facebook Twitter Pinterest Gareth Southgate will not want his England squad to be united or divided by those that are just friends or club team-mates. Photograph: Paul Ellis/AFP/Getty Images

In a newspaper column he wrote before England’s doomed Euro 2016 campaign, Rio Ferdinand mentioned the cliques which were immediately apparent upon his introduction to the England squad as a teenager. “You had [Alan] Shearer’s table and all his mates,” he said. “You had the Liverpool table and all the dregs like a couple of Arsenal and a couple of West Ham like me. Then there was the United table.”

His description of a squad divided was more or less confirmed by his fellow West Ham alumnus Dean Ashton, who seemed genuinely baffled by arrangements when he was called up by Steve McClaren in 2006. “I was warned beforehand that it [the squad] could be a bit cliquey – with the Liverpool boys sticking together, Manchester United, Chelsea and it very much was like that,” he recalled. “There was very much a feeling of when you first go into a classroom and no one really wants to talk to you. I mean, I was there for a few days, and there were some senior players that didn’t speak to me for the whole time I was there, which I just found totally bizarre.”

In an interview published in the Guardian last year, the former England rugby team psychologist Jeremy Snape cited Leicester City’s unlikely march to the Premier League title as the very antithesis of a team suffering from the adverse affects of a tribe being rent asunder by internal cliquishness. “The excitement of doing something special would have galvanised their individual differences, focused their minds on strategies and roles, and maintained their physical training until the very end of the season,” he said, before warning that future difficulties would lie in “maintaining that hunger and selflessness when so much in their lives will have changed”. Sure enough, shortly into the following season the cracks began to appear.

A thoughtful man and manager, Gareth Southgate will be aware of the need to abolish cliques in his squad while simultaneously treating his players like the grown men they are. In 2015 as head of the England youth team set-up, he was forced to deny allegations of racial divisions in the under-20 squad in the face of fairly incontrovertible evidence to the contrary. In photos published by several newspapers, either through accident or design the boys in question happened to be dining at a couple of round tables. All equal as squad members, the white players were seated together around one of them while their black team-mates occupied the other.