Egypt and Israel have spent more years as neighbouring countries at peace than at war.

For most of the past four decades, there has been an Egyptian embassy in Tel Aviv and a corresponding Israeli mission in Cairo.

This is normality to those born or who have come of age in the years since 1978.

But it is easy to forget how momentous a decision it was for President Anwar Sadat to fly to Israel and — in a 60-minute speech at the Knesset —invite Israelis to live alongside their Arab neighbours in “full security and safety”.

He was the first Arab leader to utter those words, barely five years since thousands had been killed fighting in the Yom Kippur War. The deal was a major motive behind Sadat’s assassination — and yet it survives.

It was severely tested at the beginning of this decade when, with the Arab Spring in full bloom, Sadat’s successor Hosni Mubarak was toppled. For a brief period in 2011, Egyptian public discourse was freed — and a lot of it was hostile to Israel.

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In August, three Egyptian soldiers were killed by Israeli troops as they crossed the border in pursuit of militants believed to be responsible for a series of coordinated terrorist attacks in southern Israel.

Then, in September, Israeli diplomats had to be airlifted out of the Cairo embassy after protesters armed with sledgehammers and battering rams broke into the building and tore down the Israeli flag.

At one stage there was only one door separating embassy staff from the angry mob outside.

Relations have improved markedly since then.

Because this is not a conventional relationship, we do not see Israel and Egypt do the things most countries do when they want to demonstrate how much they get along.

We are not soon likely, for example, to see Egyptian flags line the streets of western Jerusalem in preparation for a visit by Egyptian President Abdel Fattah el-Sisi, just as they did before Sadat’s Knesset appearance.

But the two do cooperate extensively behind the scenes. Egyptian intelligence officers are the interlocutors of choice for resolving disputes between the various Palestinian factions, while Israeli military expertise has been a silent, crucial partner in the Egyptian government’s battle against Islamist forces in northern Sinai.

And Prime Minister Benjamin Netanyahu visited Egypt for talks as recently as this spring, although it was kept secret for many months.

A transactional relationship it might still be, but both sides have good reason to keep it afloat.