[Sans-Culotte]

I do not understand why they sing it at all?

[Retrofitted]

Because, back in the 80s, they had a winger named Martin Offiah , whose nickname was "Chariots" (get it? "Chariots Offiah"? "Chariots of Fire"?)

Anyway, they sang it as tribute to him and it just stuck. Ready for more rugby silliness? This song is mostly sung at one -- count 'em, ONE -- location: The England national team playing in Twickenham. So all of this is about singing of a song, meant to honor a black player, in one match location.