Smallman1 I said ‘bigger’… as in, best supported, not historically most trophy-winning.
https://onefootball.com/en/news/gds-more-milan-fans-in-italy-than-inter-the-breakdown-region-by-region-37491563
Milan are bigger than Inter.
And here are your stats for the UK:
https://www.statista.com/statistics/890430/fans-of-premier-league-clubs-in-england/