It's becoming a national sport: yet another racist Ukip crank publicly vomits out their prejudice and we all parade our disapproval. Twitter hashtags are devised; internet memes are created; the offender is spammed with outraged messages. It's difficult not to be reassured by the backlash – despite Ukip's audacious attempt to inject fear and prejudice into the heart of political life, racism is still confronted in modern Britain. But it is relatively easy to take a stand against overt racism; only outright bigots will quibble with you. The danger comes if we are just patting ourselves on our backs as a means of self-congratulation, flaunting our credentials as decent human beings and failing to tackle the more subtle, pernicious forms of racism that scar our society.

The latest Ukipper to drag their knuckles over social media is William Henwood, a Ukip council candidate in north London, who made the fatal mistake of combining racism with an attack on a well-liked figure. If Lenny Henry, suggested this bigot of the moment, "wants a load of blacks around, go and live in a black country". Condemnation has rained down from cabinet ministers and the Twitterati alike, and quite rightly so. But there has been significantly less coverage of the issue that triggered Henwood's outburst in the first place: a scandal over race that Henry has been energetically attempting to force on to the agenda.

Last month, Dudley's favourite son delivered the annual Bafta Television Lecture. The television industry, he pointed out, is woefully unrepresentative of British society. While black and minority ethnic Britons make up 14.5% of the population, representation in the industry had shrunk from 7.4% in 2009 to 5.5% in 2012. The TV Collective – a membership organisation championing diversity among creative media – has launched a video about shared ethnic minority experiences. "You're not like other black people," one was told; "you're not right for the lead, but it'd be good to keep you in for colour," was another experience. How depressing that – more than 13 years after the BBC's then director general Greg Dyke assailed the corporation for being "hideously white" – we're actually going backwards.

A confession: it wasn't an issue I'd chewed over much myself until I took part in a panel discussion at Bafta's grand London headquarters last month. No offence to Bafta, but I expected a pretty tame event followed by a free glass of red wine before we all went on our merry ways. Instead, I experienced a full-scale revolt from a furious audience of actors, producers, script writers and other industry professionals. Why was there so much chatter about diversity, the audience demanded of the panel, yet so little action? Experiences of being sidelined were shared; one actor expressed her dismay at being typecast as "angry black woman" for the past 20 years.

Take Carlton Dixon, an in-house producer in comedy and entertainment at the BBC for 14 years. He recalls being the only black producer in the department for his entire time at the BBC. Invariably, black writers would only be matched up with black presenters and actors, depriving them of work in a largely white industry. When surveys suggesting a surge in non-white workers led to temporary outbreaks of self-congratulation, embarrassed silences would follow when someone pointed out it was down to an increase in canteen staff and cleaners. "We may be black but we're British, just like our white counterparts," he says. "But we're seen as colour first, that we just happen to be British."

Dixon is keen to point out that the worst offender is by no means the BBC, a corporation he happens to love working with. He recalls going freelance and approaching a company for a joint venture. "What black ideas have you got?" they asked him, suggesting that his "best chance is to give us black things".

Then there's the freelance editor with a distinctive African name who was told by a post-production supervisor at one independent company that her CV was taken out of a shortlist of four and not even read. She tells me of commissioners describing stories involving minorities as "niche", and being dropped as a result. No wonder so many of our talented black actors have had to flee across the Atlantic in search of work. "A lot of black British actors feel there's a lack of opportunities in the UK," as actor Colin McFarlane put it a few years ago.

Whenever this issue is raised, it is met with a chorus of "surely the best people should be selected for the job". But that is exactly the cry of ethnic minority creative types. The whole point is that prejudice is a form of selection, filtering out those who don't fit in with an overwhelmingly middle-class white milieu.

It matters because TV sets so much of our cultural agenda; it helps us paint a portrait of how we see our country. We should all be able to see people like us on our screens, who go through experiences we can identify with. But it is also enriching for viewers of all backgrounds to see a wide range of lives and stories, including those far removed from our own experiences. If TV is dominated by a nearly homogenous elite, we end up with crude, stereotypical and negative portrayals of minorities, narrowing our horizons and fuelling prejudice.

Little wonder there is growing impatience at periodic bouts of self-flagellation over diversity by the TV elite, followed by all too little action. Lenny Henry has launched a petition lobbying Ed Vaizey, the culture minister, to ringfence money for ethnic minority productions and programmes (as is the case for British regions) on UK TV channels. The scandalously widespread dependence on unpaid internships must surely end, too: they filter out those without well-off parents, and favour those who have the financial means to work for free. The recently established Creative Access has provided 150 paid internships for ethnic minorities in the creative sector since April 2012, and good on them. We need more paid scholarships, too, not least given TV is increasingly recruiting those who had the money to pay for expensive postgraduate courses.

Of course this scandal of underrepresentation is not limited to TV. Just 27 of our 650 MPs come from minority backgrounds; only one in 16 top company board members; and there are indefensibly few high-profile minority journalists. Yes, all this will be harder to tackle than simply tweeting our revulsion at the outright racism of Ukip's grassroots. But when minority voices speak out and demand change, all of us – whatever our backgrounds – should listen, and act.

Twitter @owenjones84

• This article was corrected on 28 April 2014. Ed Vaizey is not secretary of state for culture, media and sport, as originally stated. He is minister for culture, communications and creative industries. The article was further amended on 2 May 2014: the earlier version referred to Creative Diversity Network where it should have said Creative Access.