Terror risk is ‘price paid for our freedom’, former GCHQ chief tells Shropshire audience

Sir David Pepper, who was director of the British intelligence agency between 2003 and 2008, made the comments in a wide-ranging talk at Coalbrookdale's Enginuity Museum on Thursday evening.

Sir David, who joined GCHQ in 1972, offered an insight into the difficulties faced by the intelligence services in keeping the country safe, as well as the innovation required to stay one step ahead of their targets.

The talk looked at the development of the service and touched on some of the difficulties British spooks will face in the coming years.

Anyone who thought the lecture would be a tally-ho, James Bond-style romp through British spying was immediately put on notice when Sir David offered up the reality of the job the country's spies have to contend with.

He said: "This is serious stuff. Some of what I talk about may sound like boys' toys but this is about keeping our nation safe."

Taking questions from the public Sir David outlined the difficulties of tracking terrorist targets, the possibilities and the drawbacks of the internet, and the responsibility felt by the security services to keep people safe.

Speaking about this month's London Bridge terror attack, which saw eight people killed and dozens seriously injured, Sir David said: "I feel very great sympathy for my former colleagues, particularly in the security services who when an attack like that happens will feel like they failed.

"Going back to the London bombing in 2005, there was a tremendous sense of 'we have let the country down' in the security services."

Outlining the difficulties faced in tracking potential terrorists Sir David explained that a team of 30 people could be needed for round-the-clock surveillance on just one target, and added: "We have got to be lucky every time – the terrorists only have to be lucky once."

He said: "Think about the most recent attack. It could have been decided upon an hour beforehand and there is absolutely no way you can prevent that and if you want to live in a free society you have to accept that risk."

Asked about the role technology companies such as Facebook and Whatsapp could play in preventing terrorism and if they could do more Sir David said: "My gut feeling is they are not doing as much as they should and could but I do not think they will close down the programme entirely."

Sir David said that the internet would continue to pose problems and opportunities for spies.

He said: "The internet is in many ways the greatest opportunity the spies have ever known, however it is also the place that presents the greatest threat to our way of life."

Sir David also talked about concerns over the impact of cyber attacks, using the example of the 'stuxnet' computer worm, as one of the ways in which government facilities can be targeted.

Although never officially confirmed it is believed that stuxnet was a jointly created American-Israeli cyberweapon.

It has been widely reported that the worm was used to attack the Iranian uranium enrichment facility at Natanz in 2009. The worm was able to take control of centrifuges used in the enrichment process and damage them by raising and lowering the speed they operate at.

Sir David described the worm as "really quite a dangerous piece of software" and added: "One of our worries about national infrastructure is could an enemy disrupt our critical national infrastructure ahead of an attack?"

Sir David was made a Knight Commander of the Most Distinguished Order of Saint Michael and Saint George in 2005.