A BBC disclaimer notes that "the GAIA Organisation portrayed in the series Edge Of Darkness is entirely fictional and has no connection with the Gaia Movement or the publishers of Gaia books".
Be that as it may, the "Gaia Theory" itself is certainly a popular one. Those interested will find stacks of Gaia movement on the net, but for a general overview perhaps start with:
GAIA THEORY : SCIENCE OF THE LIVING EARTH BY DAVID ORRELL
Edge Of Darkness is also notable for it's nuclear techno-babble. Those interested in how a nuclear reactor actually works might like to take a look at a briefing page by The Union Of Concerned Scientists:
HOW NUCLEAR POWER WORKS
It would seem that the symptoms of radiation sickness as seen in the series were similarly well-researched:
THE EFFECTS OF RADIATION SICKNESS
If that's disturbing enough to give you nightmares then you can take solace in the fact that Edge Of Darkness was set more than fifteen years ago and the chances of plutonium theft by terrorists is now quite slim. Right?
THE NUCLEAR TERRORIST THREAT BY KEVIN O'NEILL
All too depressing? Well here's one final piece of Edge Of Darkness related research that will really scare you...
Articles, links and further research can be submitted via email to the Northmoor Security Director. Discussion of the subjects raised in the series welcome on the Message Board.