HOW can a story affecting Britain’s national security be relegated from newspaper front pages one day to a non-event the next?

How can an opposition front-bench demand for an inquiry be simply ignored and left to lie without protest?

Labour shadow foreign secretary Emily Thornberry demanded an immediate inquiry on Sunday into the scandal of an Israeli embassy official discussing with a civil servant the “need” to “take down” MPs sympathetic to Palestine.

It was an open-and-shut case. Senior political adviser Shai Masot was caught on video in conversation with former Tory ministerial aide Maria Strizzolo, who resigned yesterday from her subsequent position at the Skills Funding Agency.

They were the victims of a classic media sting carried out by an undercover Al-Jazeera journalist, but, unlike previous operations, this is being smothered.

The Foreign Office wasted no time in accepting Israeli ambassador Mark Regev’s apology and assurance that Masot was not acting on behalf of the embassy or his government before considering the matter closed.

Israeli daily Haaretz weighed in yesterday with knocking copy from Anshel Pfeffer, belittling Masot as a Walter Mitty type, a silly young man showing off in front of a woman by pretending that his influence and powers are greater than they are.

Pfeffer gave a potted biography of “a persuasive young man who could wear a suit and hold a glass of wine at receptions” and was then appointed a “senior political adviser” to then deputy ambassador Eitan Naeh, which amounted to “a grand title for an embassy dogsbody.”

He asserted that Masot would never have been allowed access to MPs but for chronic understaffing at the embassy and Naeh’s bad judgement.

“Whatever cloak and dagger operations might exist against anti-Israel activists in Britain do not target junior Tory ministers and do not operate from official embassies,” the Haaretz journalist boomed.

He didn’t disclose, however, where they do operate from or how he knows. Well, that’s the line from Tel Aviv, but Britain’s hardnosed media, well versed in the Mandy Rice-Davies attitude to official denials, wouldn’t fall for that. Right?

Wrong. The usually rigorous Daily Politics on BBC TV gathered Labour backbencher Lucy Powell, Tory MP Nadhim Zahawi, Jewish Chronicle political editor Marcus Dysch together with presenter Jo Coburn to agree that there was nothing more to be said.

Powell suggested that Thornberry’s inquiry call could be dispensed with because her demand had been for an “informal inquiry,” which rings strangely in light of the shadow foreign secretary’s reference to a “national security issue.”

For Labour, there is also the issue of the relationship between Masot and Labour Friends of Israel chairwoman Joan Ryan, who played a prominent role in the assiduously stoked non-story smearing Jeremy Corbyn with alleged tolerance of anti-semitism.

What lies behind Masot’s claim to have a £1 million fund to send Labour MPs off on “fact-finding” jollies to Israel?

The Israeli government has long been irate over growing support for the BDS (boycott, disinvestment, sanctions) campaign in support of Palestinian national rights.

Is it so unbelievable that a state that previously secreted assassins in its embassies to liquidate perceived enemies would stoop to dirty tricks to undermine BDS backers?

Or that it would rely on friends and supporters in the media to discredit a convincing case that the embassy in London is behind such tricks?

Questions persist over the role played by Israeli officials in Britain that must not be swept under the carpet. MPs should show some political backbone and demand answers to those questions.