Now and then I get letters making the point – with various degrees of firmness – that all ethnic groups are capable of diversity misdemeanours. I wonder why they are sent; this column has never pretended otherwise. Still, it’s good to keep reminding ourselves that such matters are complex.

My column of a fortnight ago is a case in point. It concerned a large group of students going to a nightclub and all gaining entry – save for three black male teenagers who were stopped by the doorman. The black newspaper the Voice has documented other such cases. Indeed Jermain Jackman, winner of the BBC talent show also called The Voice, has spoken of being denied entry to a nightclub hosting the after-party for one of his own gigs.

The column raised various questions: was this racism? If so, who was to blame – door staff acting on their own warped initiative or managers issuing dodgy instructions? A bit of both, probably. The column prompted former club doorman Paul to get in touch.

“As your article suggests and I am ashamed to confirm, black men were targets for racism,” he said. “We, as a team, were under specific instruction that no groups of black lads were allowed in. There were flashpoints, rightly so, regarding this – but (this is no attempt at justification) we had instructions from the people paying the wages, whose club it was and who selected and chose the (unpublished, obviously) door policy. Sad fact of life I never agreed with but, shamefully, personal feelings were superseded by my need for gainful employment.”

Here’s his twist. The club owners – architects of the noxious policy – were of mixed heritage. The “door picker”, entry supervisor, was black. “I was the only white doorman,” he said. “I was the only one ever accused of being racist. Why? Because I’m white? Because I was the public face of some bullshit agenda.” Which shows that when power and morality diverge and the air is rendered poisonous everybody then suffers in some way.

Is discrimination in this context as easy as that? It seems so. I spoke to another doorman who said he had never been told to keep black lads out, and that he wouldn’t do it anyway. But what about Travellers? “I’ve been told not to let them in.”