Yes, I was remiss in mentioning that it also needs 50%...

Yes, I was remiss in mentioning that it also needs 50% acceptance of individual shareholders, regardless of their holding size.

The 75% acceptance rate (by number of votes cast relating to the size of one's shareholding) AND the 50% acceptance rate of individual shareholders (regardless of their holding size) are BOTH based on the votes that are actually cast on the day (i.e. based on those who actually bother to participate -- in person or by proxy).

The larger point I was rather inelegantly making was that if there's a low-ish participation (not uncommon), then those who do participate end up having a larger say in the outcome than would otherwise be the case. In practice it can translate into the larger holders, who are often more engaged by virtue of their large holdings, achieving a larger-still say because of the dynamics of apathy around many of the small holders who don't bother participating.
It will be interesting to see the participation rate when the time comes to vote.