I hate it. Overplayed and overused. It's as bad as the American and Canadian national anthems to me

The point of a national anthem is not for it to be a good song. It represents a nation, change it if you can, but if you can't, that doesn't mean you can't sing it out of respect, even if you don't believe in it. 

its WAY better than the american, after all its beethoven and schiller...

Yes, in Canada we hear it every morning, sometimes again for special days/assemblies.

Update: Apparently, he normally sings the National Anthem, however, he was so swept up in the emotion of the 75th anniversary of the Battle of Britain, that he forgot to sing along.

*source is BBC Question Time.

Doesn't change that it's awful to me.

If he can't show respect to his country by doing something as simple as singing the UK national anthem, I wouldn't trust him with my vote.

I've had to listen to the anthem so many times, that I'm used to it.

I would personally find it extremely odd and somewhat disrespectul for the anthem to just be gone.

personally I would trust someone less that is happy to sing it when they don't believe in it. It is ridiculous that people put so much importance on things like anthems and flags, patriotism is a cancer on the world and governments use anthems and flags to help fuel that cancer.

And this sums up why I find this such an interesting topic. (I've not actually formed a full opinion yet, it's always good to gather outside opinions.)