It depends on what happens at the meeting. The first step for a vote to be taken at a meeting is on the show of hands. For a show of hands vote, each member present has 1 vote only and so a show of hands does not usually reflect shareholder intent indicated by proxy votes. If there are only a certain number of people at the meeting and they vote on the hands, then the outcome of the vote will be based on the hands counted unless a poll is demanded. It is not uncommon for companies to stack a meeting with shareholders holding only a small percentage of the shares on issue and pass resolutions on the show of hands.
It is only once a poll is taken that it is the number of shares held by both those present and proxies that are counted. On the poll each member has one vote for each share they hold and proxies are counted.
Regarding your question "If so can we not just fill the room with shareholders and vote it down on a show of hands?", yes potentially you could, but if that took place and the deal was voted down on the show of hands, then after the show of hands vote the Chairman (ie, management), 5 present members or shareholders controlling 10% can simply demand a poll be taken. That is why it is important to hold proxies with sufficient shareholdings in support of your vote to ensure your position can get up on a poll.
