Keir Starmer’s royal comments are significant precisely because Boris Johnson has said so little

“Whatever you do, keep the politics at your end of The Mall.” That is the message senior royal aides give to an incoming prime minister when they arrive at the Downing Street end of the wide road connecting Whitehall with Buckingham Palace.

It is supposed to work both ways: the royals keep out of politics and the politicians don’t normally interfere in things which are a matter for the monarchy. However, it has already proved impossible to keep politicians out of the intense debate sparked by Meghan Markle’s incendiary claim to Oprah Winfrey that one unnamed royal raised “concerns” about “how dark his skin might be” when she was pregnant with her son Archie. (The alleged conversations took place with Prince Harry, who has made clear via Winfrey that the Queen and the Duke of Edinburgh were not part of them.)

Labour was first to react when Kate Green, the shadow education secretary, said the claims were “really distressing, shocking”. She told Sky News: “If there are allegations of racism, I would expect them to be treated by the palace with the utmost seriousness and fully investigated.”

Keir Starmer said during a school visit in east London: “It is a reminder that too many people experience racism in 21st-century Britain. We have to take that very, very seriously.” Referring to Meghan’s claim that she was suicidal but had not received adequate support from the royals, Starmer said: “Nobody, but nobody, should be prejudiced [against someone] because of the colour of their skin or because of their mental health issues.” Although sidestepped the issue when asked if he backed Green’s call for an investigation by Buckingham Palace.

In contrast, Boris Johnson is trying to keep out of the controversy. His official spokesman refused to be drawn on an investigation, saying: “It is a matter for the palace but the prime minister hasn’t seen those interviews.”

The allegation of racism gave Labour a legitimate route into the story most of the country will be talking about. Although there has been a fierce political and public debate about immigration, the UK is regarded as more tolerant on the question of race. In recent years, immigration has fallen dramatically down the league table when people are asked to name the most important issues facing the country. Many people worried about immigration seem to think that Brexit ticked that box because the UK has “taken back control” over its borders.

However, the Tories continue to reprise their old tunes, reminding us of Starmer’s previous support for free movement as they re-fight their battles with the EU even after Brexit. Priti Patel, the home secretary, described Britain’s Black Lives Matter protests last summer as “dreadful” and said she would not “take the knee”. Her comments were seen as part of a “culture war” aimed at putting Labour on the wrong side of the argument in the eyes of the Tories’ base, including the working-class voters in the north and Midlands won over by Johnson in 2019.

Ministers have made it harder to remove statues that cause offence; appointed a “free speech champion” to oppose the “no platforming” of speakers at university events and told museums to “defend our culture from the noisy minority of activists constantly trying to do Britain down.”

Labour took the advice of the US Democratic Party, themselves targeted by Donald Trump’s culture war, and refused to turn up for a fight on the Tories’ chosen territory. So Starmer’s comments about Meghan’s claim are significant. At one level, the relative freedom of opposition allows him to say more about the huge story than Johnson.

But the affair might just allow Starmer an opening to fight back in the culture war on ground much more favourable to Labour. His words will unite his own party and might provide some ammunition against internal critics who say is too cautious.

Johnson can hardly attack the Labour leader for arguing that as a country we have been “too dismissive” of racism and mental health problems. Starmer is right on both fronts. But the Palace’s “keep out” edict will be uppermost in Johnson’s mind; if he supported calls for an investigation, he would be seen as taking sides in the war tearing the royals apart.

So he will leave that one to those at the other end of the Mall.