Who can protect UK in a cyber attack?

The skills of amateur ''cyber defenders'' are being put to the test in London this weekend, as they try to protect the UK against a simulated cyber attack.

Teams are competing in a scenario which involves a foreign government attacking the UK's financial systems.

As part of the exercise, competitors are shown simulated news reports, given briefings by the national defence community, and tip-offs by undercover operatives.

Gordon Corera reports.