Bah Gawd, comparative football histories... that's my music!
So: the most specifically proletarian sport in England is historically actually
Rugby League where soccer has a broader based appeal and spread to the middle classes based on early professionalisation and the associated meritocratic and commercial ideals.
This goes back to the 19th century. There are roughly seven modern footballs (Association, Rugby Union, Rugby League, Canadian, American, Australian, Gaelic), all of which developed out of the same initial environment around the public schools of the British Empire in the 19th century and the idea of Muscular Christianity and the game preparing boys to help run the empire. They are various standardisations of "football" which took a few decades to be codified and established on a stable administrative basis, out of the ad hoc unstandardised sorts of football games that existed beforehand. In many cases the various sports had or tried similar rules which were adopted or discarded in some other sports. Questions like scrums and offside and methods of moving the ball varied. For example Gaelic at one point had behind posts like Australian has now, Canadian experimented with something much like the Rugby League "play the ball" restart as a method of reforming the scrum before settling on the snap back.
So there were various rule sets, initially you had soccer and rugby type rules both administered by the FA until the Rugby Football Union split off over rules arguments in about 1870. The RFU was at least as successful and maybe even the more successful and popular game for a decade or two, though this period was also when both codes became mass spectator sports which brought in a lot of new money. With that new money, both the Rugby and Association codes grappled with a fundamental controversy over amateurism vs player payments, which was basically a proxy form of class conflict. The well-off felt that playing the game for its own sake was important for morality and character, and often saw amateurism as an explicit tool for gatekeeping against the lower classes who they didn't want to associate with. The working classes on the other hand expected payment in lieu of time lost at work, at the every least,. They also saw the football codes as a professional path in and of itself.
(Canadian, American, Australian and Gaelic were obviously not part of developments in England, but were local variations on similar arguments about rules. Scrums and were big points of contention. Canadian and American both developed as reformations of rugby attempting to fix scrummaging, Australian was another local variant of football with its own rules plucked from the various options that existed (it is old enough to have been codified even before the Rugby/Association split in England). Gaelic was linked to the British games specifically as a nationalist reaction against Rugby and Association football, incorporating Hurling rules and making some different decisions on other rules too.
So: Association Football's place in the world and in England is distinguished from the other codes of football by having been the one in the Empire's heartland which decisively decided the question of payment in favour of professionalisation. They made that change in the 1880s after the northern clubs threatened to leave the FA. It was
this decision which paved the way for Association Football's global dominance, the sport became very much the sport of British capitalism and the middle classes. It was meritocratic because any man with talent could play and win fame and fortune, the wealthy could own and fund teams, etc.
Critically, UK capitalism was pre-eminent in the world in this era and so British culture and business was very influential even outside of the Empire. The professional ethos of Association Football gelled perfectly with significant portions of Europe and South America's young men when the game was introduced there, usually initially by British trade or business connections. In a lot of places the sport came to replace or embed within local gymnastics club traditions and its commercial appeal was quickly pretty huge.
British Rugby of course went the other way, deciding to implement draconian rules
against professionalism. This was often explicitly about limiting the social access of the game to those who could afford to play for free.
(Incidentally, this same British amateurism ideology vs soccer commercialism thing is a big part of why the FIFA World Cup was established separately to the Olympics)
Rugby League emerged when the Northern Union of clubs broke away from the RFU and reformed the game, professionalised and created league and cup competitions. Rugby League was bitterly opposed by the Rugby Union and life bans were long the norm for anyone who played or refereed the rival code. Of course, by this stage, Rugby had lost much of its previous widespread commercial appeal in England and Association Football had already exploded and taken root in many other places.
So Rugby League was locked into its heartland in the industrial north of England, and for many decades due to ostracism by Rugby Union it was an almost exclusively industrial working class sport. The early middle class and upper class adherents largely disappeared after the split, and at most you'd find some small scale business people like pub owners still involved as sponsors and the like.
Some other places:
- Rugby League was the very proletarian sport in southern France vs Rugby Union being seen as more the landlords' sport, but the Nazis and Vichy France decisively destroyed Rugby League in France after it had threatened to swamp Rugby Union. Union became almost completely dominant in Southern France once more under an anti-professionalism "merger" ordered by Petain. Collaborationist Union officials were able acquire seized League assets, the sport was banned as a leftist corrupting influence, etc. There's a Catalans Dragons in Perpignon in the UK Rugby League comp, but they're a lot less prominent than the big Union clubs.
- The Rugby League is working class vs posh Rugby Union also in Sydney and Brisbane football, where the two codes are the traditional ones. Melbourne, Perth and Adelaide are 100% Australian football cities, where class divides were expressed between clubs within the same league rather than inter-code rivalry.
- Rugby's background in the public schools is a big part of why American Football developed in their colleges. The same ideological forces that promoted sport for young men of future standing in the British Empire also led Rugby to be introduced and become popular in US colleges. American football developed and diverged from Rugby Football, and the US higher education system was expanded with the Land Grant schools, so American Football followed.
- Rugby Union is massified in New Zealand and doesn't have class connotations, Rugby League is a more minor sport but I think it has a working class flavour there. New Zealand being wholeheartedly into Rugby Union is the single biggest reason they're so dominant - it's their whole country vs the posh parts of two cities in Australia and their player base outnumbers ours the way we outnumber them in cricket or netball.
- To my knowledge Union is fairly similarly massified in the Pacific Islands of Fiji, Tonga and Samoa - it got there first via missionaries and traders, and my guess is the pull of soccer and professionalism wasn't significant there due to the small island economies and soccer not being big in Australia or NZ anyway
- Rugby Union is more massified in Wales, very much a game of farmers and mining towns. There were long established generous methods of working around prohibitions on professionalism for Welsh Rugby Union players, with the RFU turning a blind eye to player payments as long as the Welsh Rugby Union pretended not to pay players and the RFU pretended they believed it
- Romania and Georgia are former communist countries whose Rugby introduction came from French communists rather than British influences. Romanian Rugby more or less disappeared with the end of the Nicolae Ceausescu regime that promoted it (the Romanian captain was shot at a road block during the revolution). Iin Georgia it resonated with a traditional village game called Lelo and they formed the bulk of the Soviet rugby team. The Soviets also created a stadium variant of that sport which rather resembles Rugby played with medicine balls and legal forward passes.
- I'm not sure how Rugby began in Japan but it's largely a university game with clubs heavily supported by corporate leaders who dominate at the expense of a weak JRFU
- Rugby in Argentina is pretty posh - I don't know the history here but I'd guess it came with British capitalism and shrunk to just the upper classes due to the spread of soccer among everyone else.