On Monday afternoon at Ben Gurion Airport, the no longer hidden secret revealed itself once again: ties between Israel and the United Kingdom are incredibly close and have been for decades.

The visit by Prince William to Israel, the first ever by a member of the Royal Family, was repeatedly described by British diplomats as “non-political”.

But it was taking place to underline a deeply political fact. The strategic Israel-Britain relationship — once, perhaps, the love that dare not speak its name — is now out and proud.

It is hard to exaggerate the extent to which British policy towards Israel has reversed. For most of the past seven decades, no matter how close cooperation was on a wide array of security, intelligence and military matters, the Foreign Office firmly kept a lid on revealing the full ties between the two countries.

“I’d like to be able to say how close our relationship is, but I can’t say how close our relationship is,” one former British ambassador to Israel memorably quipped.

The 70 years of unofficial royal boycott was just one overt sign of the lingering refusal to acknowledge just how well the two countries got along.

Countless examples of the strong relationship have been kept under wraps for years. As recently as 2007, when British soldiers were dying in Taliban ambushes in Afghanistan, Israel rushed guided missile launchers out of IDF storage facilities to Helmand to fill the operational gap. Britain never acknowledged the gesture.

Things have changed: joint exercises and visits by Britain’s armed forces commanders are now taking place out in the open.

The old habits are dying slowly. British diplomats still prefer to speak about trade rather than security. But the notorious “Arabist” tendency of the Foreign Office is — almost — a thing of the past, as is the patronising attitude that Israel somehow had to “deserve” a royal visit by first making peace with the Palestinians.

Such was the firmness of the royal boycott that there were opposing views in Israel’s Foreign Ministry over whether it should continue issuing invitations to the palace when they would only be met with condescending smiles and obfuscation.

“We should stop humiliating ourselves. Britain needs us more than we need them. If the Queen isn’t coming it’s her loss,” was the view of one Israeli diplomat.

“Israel should have a royal visit,” was the view of another, a former ambassador to the Court of St James. “The royals have been to most of the countries in the world, including many dictatorships and most Arab nations.

“We should insist that the boycott of Israel end and Britain stop treating us like a secret mistress.”

The Queen will not come. At her age, she no longer makes major overseas trips. Israel’s consolation prize, the second-in-line to the throne, was as good as it gets in 2018.

The royal visit did not necessarily register as a historic event for all Israelis.

The union flag flew from lamp posts in three Jerusalem streets this week — but they were flying Bulgarian flags for the arrival of Prime Minister Boyko Borissov just a day before. Plainly, Jerusalemites are used to visits by world leaders every week.

Pictures of William were on the front pages of most newspapers, but he was generally not the main story, crowded out by news of Syria, Gaza and the ongoing investigations into the Israeli Prime Minister.

But the crowds that gathered — on Rothschild Boulevard, for example, to see William meet Netta Barzilai — were genuinely enthusiastic.

Some politicians jostled for an invitation to one of the handful of events he attended.

But aside from the event with Netta, there were no crowds on the streets, unlike some countries which host royal visits where people are anxious for a glance and a sprinkling of royal stardust.

For many Israelis there was a feeling that the visit was taking place decades too late; if only it had happened a generation ago and if only it had been the Queen, they said, it would have been different.

Israel’s President Reuven Rivlin is one of those veteran Israelis who remembers living in Jerusalem under curfew with British soldiers patrolling the street outside his home.

Being the first Israeli president to host a member of the Royal Family certainly had historical resonance.

For Prince William’s other Israeli host, the visit had a much more immediate political meaning.

Prime Minister Benjamin Netanyahu has been claiming for years that the long line of world leaders queuing up to meet him are proof of his “strong leadership”.

Being the first prime minister to welcome an official royal guest in Jerusalem is an achievement he can add to a string of others, including persuading Donald Trump to pull out of the Iran deal and move the US Embassy to Jerusalem, and being invited to Moscow as guest of honour on Russia’s Victory Day.

Mr Netanyahu’s thesis, as Haaretz’s Noa Landau recently put it, is that “no ‘diplomatic tsunami’ of isolation will result from the absence of a peace process”.

The world will embrace Israel, the notion goes, even if the occupation and the lack of talks continue forever.

The deeply pro-Israel Margaret Thatcher was the first serving British prime minister to visit Israel, in 1986 — and she overcame resistance from the Foreign Office to do so.

But even she made sure she arrived while the dovish Labour leader Shimon Peres, and not  Likud’s hardline Yitzhak Shamir ,was in office.

Today, there is no concern about staging the first royal visit during the term of another Likud leader, one of the most right-wing the country has ever seen. It feels like Britain is less concerned by the unresolved Palestinian issue and wants to focus on other aspects of its relationship with Israel.

That was why, besides one very mild remark at a Likud faction meeting last week, Mr Netanyahu did not persue the issue of the Duke’s visit to the Old City of Jerusalem being described by Kensington Palace as being in “the occupied Palestinian Territories”.

It is a tiny price to pay for boosting his credentials as a geopolitical master — the first Israeli leader to break Britain’s royal boycott.