In an interview with RFE/RL correspondent Ahto Lobjakas, he was asked, among other things:
...RFE/RL: The Security Service has over the past two decades become less concerned with espionage, and now mostly focuses on counterterrorism. Why is that?
Andrew: That's right. It's a comparatively sudden change. MI5 was founded exactly 100 years ago this month, solely as a counterespionage network. Nowadays, on its 100th birthday, it only spends 3.5 percent of its resources on counterespionage. Espionage is still going on. But espionage by, for example, Russia is plainly not as threatening to national interest now that the Cold War is over as it was at the period when people legitimately wondered whether the Cold War would turn into hot war.
So it's overwhelmingly a counterterrorist agency. But how it got into it is, I think, not generally known. The first major terrorist target of the Security Service was actually Zionist extremists -- Menachem Begin, for example, the future prime minister of Israel -- after blowing up the British headquarters in Palestine, the King David Hotel, after blowing up the British Embassy in Rome. They then planted a huge bomb in Whitehall [British government headquarters], which failed to go off.
Note, that second operation, at Whitehall, was not an Irgun operation.
According to Eli Tavin, Commander of the Irgun Abroad (Europe), there was only one planned operation, an attempt to assassinate Genral Evelyn Barker, in which Ezer Weizmann took part. Other operations considered were the bombing of underground telephone wires near the City of London; demolition of a tunnel under the Thames; an attack at the telegraph center at Cornwall; a recreation camp intended for veterans of the Palestine Police and the ocean liner Queen Elizabeth. None of these moved beyond the planning stage. See "The Second Front" (Hebrew), p. 173.