I saw an interview this morning on BBC World, where Tim Sebastian interviewed the author of 'The Crew', and 'The Barmy Army' (I forget yer man's name, now).

But yer man was of the opinion that peer pressure, exerted by the fans themselves, could hold the key.
He cited the time during the late '70's where darker skinned footballers were subject to the throwing of bananas.
He reckoned that peer pressure effectively put an end to that; the point being made that as it was not being tolerated on the terraces by the majority of fans, the perpetrators were being 'shamed' into desisting.

Interesting point, given that the guy is a self-proclaimed National Front sympathiser, and therefore, probably knows what he is talking about.

B.