Quite a lot of racist speech is legal in the UK, while some racist speech is against the law.

So some overtly racist groups are legal (eg BNP and Britain First, as are Hizb-ut-Tahrir). Others are proscribed, like Isis, al-Qaeda and National Action, as violent terror groups.

Under the 1986 Public Order Act, passed by the Thatcher government, it is an offence to publish or distribute material *intended* to stir up racial hatred, or thought likely [by the reasonable citizen] to stir up racial hatred whether or not that is the intent

Clearly, this is used with quite a lot of discretion. (Most of what Britain First does and says has this intent - it is largely the purpose of the organisation - but the law is seldom used against its members (except for specific acts of intimidation, threat and violence)

I personally find it a little surprising that Paul Golding was not deemed to have crossed that line when he issued this threat by media press release to all elected Muslim office holders after the Mayoral election of 2016 saw Sadiq Khan elected in London
https://www.google.com/amp/s/www.independent.co.uk/news/people/sadiq-khan-britain-first-london-mayor-threaten-direct-action-a7047991.html%3famp

Reasoned UK published an interview in which David Starkey made racist remarks. That is not disputed by anybody serious. Here is Starkey apologising for the most noted racist phrase he used in the interview. [If slavery was genocide], "there wouldn't be so many damn blacks".

Darren Grimes has said he regrets publishing this racist content. He published it by mistake. He didn't notice the overt racism, either in conducting the interview, nor in whatever editorial process he had (or perhaps didn't have) when publishing + broadcasting it.

Grimes account suggests he was
* Starstruck/meeting his "hero"
* "learning the ropes" as an interviewer
* inexperienced as a publisher (untrained on law for publishing? )
* still has weak understanding of what racism is + poor radar for noticing it when he hears it/publishes it

There is a broad consensus this does not seem a matter for police, or could meet prosecutable standard (Many have intuitively focused on Grimes role the interviewer - a red herring - rather than as publisher). But few people think inciting hatred test met https://twitter.com/sundersays/status/1314821100434526208?s=19

George Peretz QC goes through this in detail. (Several suggestions have been made that the police may be obliged to investigate a complaint, though very unlikely they or CPS would then pursue it). https://twitter.com/GeorgePeretzQC/status/1314853551668068355?s=19

Darren Grimes seems much more chuffed than chilled b range of people (almost everyone) who agree that his publishing racist content (by mistake) does not meet the criminal threshold for racist content inciting hatred. He has moved on from the 'try not to publish racism' lessons

The police assessment seems v.unlikely to turn into a formal investigation. Nobody anticipates a prosecution.

Could be a comms issue about how the police explain what they are doing (if feel obliged to assess a complaint) or an operational one (was this necessary?)

But core of free speech, hate speech & social norms issue is mostly *not* the legal boundary - as egs of BNP, Britain First & v.overt racists on Twitter show. [Another reason police intervention in this high-profile but not comparatively extreme eg of overt racism is a bit odd]