derkleineprinz ,
Cootuk is correct, I have attended many AGM's as a guest, having signed in as such, and being given a different type of card (non voting), or asked to sit in a section reserved for press and guests, ie non voters.
This is permitted under UK company law, and the only time this was not permitted, non shareholders were admitted after the formal part of the meeting had finished, about 3 minutes into the meeting, and before the company presentation.
I have attended several AGM's where the register was not checked at all!