Holography is still alive and well, although very much misrepresented these days as anything that is remotely 3D or looks like Princess Leia unfortunately gets called a hologram. There's a lot of the 'old timers' as well as many new innovators active on Facebook in the 'Holography' group and the 'Holography forum'
A bit of a stab in the dark but i'd guess the exhibition you went to in London was by 'Light Fantastic'?
Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.”... Douglas Adams 1952 - 2001