Just because you or some people you know haven't heard of something does not mean it was, or is, a secret and while the internet age has seen more interest in the group, their existence was no secret and Bilderberg Group meetings have been referenced in the mainstream press for decades now.
For example, the below was published in The Guardian, on May 26, 1989:
"Mr Paddy Ashdown is not yet wholly at ease with the trappings of office, even if the office in question is only that of leader of the Social and Liberal Democrats. Attending the Bilderberg Conference of European political leaders in Spain last week, he was deeply impressed by the splendour of the official cars and the intensity of the security precautions laid on for his arrival. Reaching the conference headquarters at last, he sank into a chair and said to his neighbour: 'Hello, I'm Paddy Ashdown.' The neighbour smiled diffidently, put out his hand, and said: 'Hello, I'm the King of Spain.'"
Which (along with many other historical news reports) makes it hard to believe you when you say that, in 1996, The Guardian said the existence of those meetings was a figment of David Icke's imagination or that it's existence was first revealed by Tony Blair in 1997.