one to one is just 'evens', you put a pound on, to win a pound back (and your original pound, then minus taxes on the winnings, the government do like their, after they have already taxed your earnings).
Does not mean he's won. Could be the bookies wanting to get as many people to bet on Anthony to win, as they 'expect' him to win, then another housemate does win (or even shifts the odds, by that stage, the bets have been made), so the bookies earn a little bit more cash.