I think most, like me, won’t know too much about Union Saint-Gilloise - or, to give them their full name, Royale Union Saint-Gilloise. So I went looking. It’s quite a story.
Got promoted, via the play-offs, to the Belgian top flight in Summer 2021. Their first stint in the top flight in 48 years. Incredibly, they then finished at the top of the top flight at the end of the regular season.
Sadly, for them, the Belgian League has a play-off system/Championship Round in place and, at the end of the play-offs they finished second and thus go into the Champions League Qualifying Rounds.
Their ultras are knows as the Union Bhoys.
Tony Bloom, Chairman and majority owner of Brighton, also owns 75% of Union SG.
According to Wiki at least.