It had all the makings of a perfect Tel Aviv evening: dappled sunshine, lights strung between lofty palm trees, music spilling out onto the lawns of the family home and a jubilant wedding attended by guests from around the world.

Among them was Deborah Clayden, a 51-year-old teacher from London, who had travelled to Israel with her elderly aunt and mother for what she hoped would be a joyful few days away to celebrate her cousin’s nuptials.

For most of Thursday night, that is exactly what it was. But just after 3am, barely an hour after she climbed into her hotel bed, mother-of-three Clayden was jolted awake by the sound of a siren going off on her phone. An app, which everyone in Israel is told to download when they arrive, told her to find shelter within 90 seconds.