U.K. spy chiefs pulled out of the shadows

London The heads of Britain's three most powerful spy agencies will answer questions from U.K. lawmakers Thursday for the first time ever in view of the public.

Sir Iain Lobban, head of the NSA-equivalent GCHQ, MI5's Andrew Parker and MI6's Sir John Sawers find themselves in a position none of their predecessors ever knew. Until recently, even the identities of the MI6 bosses were secret.

So why are they now being put in front of cameras to account for their agencies practices?

"They've not done this in the past," professor Richard Aldrich, an expert in intelligence and security services at England's University of Warwick, told CBSNews.com ahead of the spy chiefs' session before the Parliament's Intelligence and Security Committee (ISC).

He explained that for the agencies' entire existence, their work has been conducted largely in secret -- they have never had to explain how they do it, where the boundaries are drawn and, in his words: "If you leave a vacuum, someone will step in and explain it for you, and the person who stepped into the vacuum was Edward Snowden."

The former NSA employee's move to drop the curtain around the U.S. agency's vast global surveillance programs has highlighted and perhaps expedited, in Aldrich's mind, a trend that was already snowballing.

"The intelligence agencies are conscious that they no longer own intelligence. It has escaped into society and they have to explain themselves," he said. "All sorts of organizations have intelligence now. It's a great ecological system, which involves everybody and they can't just hide in a hole anymore."

NSA surveillance program

While the ISC's mandate is focused on the practicalities of running Britain's intelligence agencies -- costs, efficiency, etc. -- the Members of Parliament will also have to acknowledge Thursday the scandals of the day. The spy chiefs can expect some tough, if cordial, questions about the extent to which Britain helped the U.S. spy on other European nations -- snooping which has seen leaders in Germany and France rage with indignation.

Britain stands alone in Europe as an exclusive member of the American intelligence apparatus, and there have been accusations that GCHQ and NSA essentially enabled each other to spy on their own respective nationals; getting around each nation's domestic laws by having partners on the other side of the Atlantic do the actual spying.

A former British intelligence analyst, who spoke to CBSNews.com on condition of anonymity, said those claims are exaggerated, and that in his own experience at a senior level on the front lines of intelligence-gathering, working closely with American counterparts, "there were constraints around us" for sharing information about citizens of each others' countries. "And once you put walls in, it is very hard to take them out."

The former analyst said he "would be quite surprised" if analysts at either the U.S. or U.K. agencies were breaking the rules in any kind of systematic or regular way.

Oversight, nonetheless, is essential for any government body. As former U.K. Home Secretary David Blunkett put it Monday in an interview with The Guardian: "Human nature is you get carried away, so we have to protect ourselves from ourselves."

Blunkett called for an update to the 2002 law known as Ripa, which lays out the ground rules for Britain's spy agencies and how they conduct their work.

"We were moving into an entirely new era. We were at the very start of understanding what we were dealing with, and understanding the potential. You have to have constant vigilance and return to these issues on a regular basis because the world changes and you should be prepared to change with it," said Blunkett. "I think Ripa needs trimming back. It is being used for things for which it was never intended."

But even if the lawmakers press hard for the three men in front of them on Thursday to give honest and truthful answers, and walk away with the unanimous belief that Britain's spy agencies do require closer scrutiny and laws should be changed, Aldrich said their best intentions may be simply be too slow to convert into meaningful action in a national security environment that evolves in hours and days, not months or years. It takes, Aldrich noted, about three years for new legislation to clear the British Parliament and be signed into law.

He also doubts that the agencies have actually overstepped their bounds, as Snowden and others have asserted.

"They have some very creative lawyers who allow them to go right to the limit of what they're allowed to do," he said, adding that given the incredible level of complexity involved in intelligence gathering, both technically and legally, "even if we pass new legislation, frankly I don't think the parliamentarians would understand what they were passing."

"The Snowden story is actually quite an optimistic story," concluded Aldrich. "It's not about the end of privacy it's about the end of secrecy. The people who are really worried (about the practices revealed by Snowden) are not the Guardian readers, they're the officials in White Hall (London) and Washington."

Aldrich admits that the future is likely one where individuals can expect to live with a lot less personal privacy. But he said what the Snowden scandal, and the first-ever public question and answer session with Britain's intelligence chiefs, both demonstrate, is that the most powerful people and agencies that govern our lives are in many ways being forced into the light with us.