SNEERING that a woman wearing a burqa looks like a letter box or a bank robber wasn’t a slip of the tongue by Boris Johnson.

This provocative slur represented a steely-eyed calculation that it would bring him the double benefit of keeping him in the headlines, despite his resignation as foreign secretary, and of sending a dog-whistle message to Tory Party Islamophobes that he’ll be their man when the time comes for Theresa May to go.

Equally calculated has been his dogged refusal to apologise in response to anger from within Britain’s Muslim communities, who recognise opportunist cultural oppression when they see it.

Johnson tries to have his cake and eat it by insulting women who wear the burqa or niqab while voicing opposition to Danish, French and Dutch legislation banning face coverings.

In this way he affects to emphasise his liberalism while cloaking anti-Muslim prejudice in what he defends as light-hearted humour.

He has previous in this area, having demeaned black British children in a newspaper article as “piccaninnies” with “watermelon smiles.”

Johnson is as nasty a piece of work as Enoch Powell was, offering a different persona but laying claim to a similar, and equally undeserved, reputation for being straight with the public and saying things that “they” don’t want us to know.

He has got away with sailing close to the wind in the past because the Tory leadership viewed him as an electoral asset and, in any case, he wasn’t alone in gleaning votes from the racist or Islamophobic gutter.

This was exemplified in the last London mayoral election when Zac Goldsmith’s campaign plumbed the depths in linking successful Labour candidate Sadiq Khan to the threat of jihadist terrorism.

Johnson’s support structure has peeled away this time, first through the principled condemnation of Sayeeda Warsi, who previously resigned as the Tories’ co-chair in protest at Islamophobia in her party, then the demand for an apology by current chair Brandon Lewis and finally – nearly two days after Johnson’s article was published in the Telegraph – by the Prime Minister herself endorsing that demand.

Born-again battlers against Islamophobia are now crawling out of the Tory Party woodwork, eager to put the boot into Johnson.

David Cameron’s former attorney general Dominic Grieve, who calls Johnson’s comments "very embarrassing,” says he would leave the Tory Party if the former foreign secretary ever became leader.

And there lies the crux of it — the party leadership. That’s why Johnson spoke as he did and why his opponents are determined to prevent him ever getting the top job.

As ever, the elephant in the room is the European Union referendum that put an end to the political careers of Cameron and George Osborne, both of whom nurse a grudge against their former friend Johnson, whom they expected to back the Remain side.

The cackling that Johnson can hear is the sound of pro-EU Tory chickens coming home to roost in the wreckage of his leadership pretensions.

As enjoyable as it is to witness Johnson’s current isolation, the battle to combat Islamophobia is far more important than transient inner-party embarrassment for shop-soiled Tory politicians.

Muslim communities continue to report a heightened incidence of racist incidents, including attacks on mosques, just as Jewish synagogues, schools and cemeteries do.

The perpetrators are invariably linked to far-right groups that are emboldened to carry out their activities openly in light of the supportive propaganda role played by mainstream politicians.

They must be called out, isolated and defeated.