MtheGM' well, Mori has said that 20% of the population want to get rid of the monarchy.( I would estimate that the actual figure is higher. i.e. I don't trust poll takers - or their motives/affiliations, and I'd love to see how they conduct these polls).
Even, on 20%, that's 10 millions plus.
So let's say only 20% of those really find "God Save the Queen" distasteful and divisive, we are still talking over 2,000,0000 people.