Mossad: "Can we borrow your passport please?" - The Jewish Chronicle

So how could the Israeli authorities get access to the details of British passport-holders?

Here are two ways: one, when people make aliyah, and another, when foreign passport-holders are approached by security services.

Sanjoy Mukherjee made aliyah last year. He said: “Once your aliyah application is approved by the Jewish Agency, you give your passport in and it’s given to the Israeli consulate in London which provides you with an aliyah permit.

"The passport is returned to you and you make aliyah after that. As I recall, my passport was there for around 10 days.”