Contract to perm is the best way by far. In the UK the contract rates are typically significantly higher, so even if the person isn't offered a job at the end they aren't bothered. Everyone wins
Contract to perm is the best way by far. For whom? It's bad for the worker because you're going to work for a company that is admitting by its behavior that it has little confidence in its abiliity to assess talent. Where else is it weak? (My experience shows that those who can't assess talent usually can't do a whole lot of other important things, too.) It's bad for the company because it limits its pool of candidat…
Typically here in London these people are already contracting, so all you need to do is convert the best ones.