The deeper significance of "Bigotgate"

What I find most revealing about Gordon Brown calling a dedicated, life-long Labour supporter a bigot, because she dared express concerns about immigration ("It was the question about immigration that I think was annoying", he said in an interview directly afterwards), is the light it throws on how the Labour party, for decades, has suppressed all criticism of mass immigration  (and of the multi-ethnic society that comes with it), not just within its own ranks, but in society at large, by branding it as "bigoted" or "racist".