While Osama Bin Laden may be dead, he said, "in back rooms and cars on the streets of this country there is no shortage of individuals talking about wanting to mount terror attacks here."
The U.K. has had 43 terror plots or incidents since 2001, authorities said, numbers that are similar to those in the U.S. All since 2005 have been thwarted and several had also been aimed at the U.S., including the recent "printer bomb plot."
Evans said preparation for the Olympics had gone well, and that the Olympics, even if an "attractive" target, would not be an "easy target."
"There is no such thing as guaranteed security," he said. "But I think that we shall see a successful and memorable Games this summer in London."
However, said Evans, "as the government said after the Brighton bombing in 1984 [an IRA attack that narrowly missed British Prime Minister Margaret Thatcher], the terrorist only has to get lucky once."
Though U.K. retains the pound as its national currency, Evans singled out the likely rise of political extremism as a result of the "Euro" crisis as a potential threat to the financial community in The City of London -- a mile-square independent jurisdiction within London.
He also pointed out three past national security risks to the financial sector-- all from the U.S. -- the World Trade Center attack in 2001, the almost forgotten bombing of the same towers in 1993, and the anarchist bomb attack on J.P. Morgan's bank in 1920.
"If I may be allowed a Rumsfeld moment," he said, "there are of course the uncertainties we can be certain about -- like terrorism, cyber security challenges and hostile intelligence activities by states. But there are also things we remain uncertain about." During a 2002 press conference, then U.S. Defense Secretary Donald Rumsfeld made a famous distinction between "known knowns", "known unkowns", and "unknown unknowns".
Intellpuke: You can read this article by ABC News correspondent Richard Esposito in context here: abcnews.go.com/Blotter/astonishing-cyberespionage-threat-foreign-governments-british-spy-chief/story?id=16645690#.T-p6wpHh7No