I think the oft-trotted out phrase 'We have to pay the top salaries to attract the top people ...' has been used for far too long, given that a large number of executives, and here is one, are effectively paid for failure.
I would have a system based on this premise -
"Ok Mr Bigshot, I perceive that you are the best man for the job, and I want you to work for me, so I will pay you £10million for your first year.
But before you get excited, know this. If you don't increase profits and productivity to the level that my board advise, then I will take nine-point-nine million pounds back from you, and sack you.
Now that should concentrate your mind into justifying your reputation which has brought you into my orbit. Of course, if you are as good as you should be, to justify that level of salary, you will have no difficulty at all in reaching the level I demand, and I shall then re-negotiate your salary for the next year - that is how we are going to do it.
I fully expect you to accept my seriously generous terms, and if you have any queries at all, please send in the next candidate on your way out. OK - over to you ... "
Most people at the bottom end of these multi-nationals get fired if they can't hack it - why should that perfectly reasonable premise not apply at the top as well?