Its a lucrative market for the bookies, for instance the list as it stands is a guessing game so plenty of cash will be put down on what is currently a lottery, then theres the usual rumour mill which sees big money put down on a punt, usually made by my mate spoke to his mate and his mate says so and so's got the job and its a dead cert. By the time the real contenders are in the mix theres a fair kitty to fall back on so then the bookies just shorten the odds and sometimes even limit the amount on individuals bets place to limit their exposure, by which time they have already cleaned up.