How far in advance do you think they'd have to book acts to duet with the contestants in the final?

The reason I ask is that there's no way on earth that they'd be able to book who they want the Monday before the show.

So, they'd have to have them booked a few weeks in advance, yes? But if that's the case, then wouldn't they have to tell them that they may not be required, depending on who gets through?

And what singer/group would be happy to clear their diary on a maybe? None, I'm guessing.

What does everyone think?

Well there'd be negotiations such as "We'll give you a solo slot to promote new material" so that's the artist in question hooked. They get promotion regardless of duetting or not.

I think they'd do that with 2 acts (e.g. Rihanna and Christina last year) then other acts would be on stand by (people the judges know/that are linked to associated record labels).

I think this was the reason why Cher was saved last year. They had probably already lined Will.I.Am to perform with her, and so they couldn't just decline it at the ready. Also for the fact Mary could have gotten the Irish vote.