Instant Runoff Voting was used for the first time by the British Labour party to elect its Deputy Leader, replacing the use of separate runoff ballots.
Party delegates include Labour Members of Parliament, trade union members affiliated to the Labour party, and ordinary party members, each group weighted to represent a third of the final vote.
Harriet Harman won in round 5 with just over 50% of the vote in a close race among six candidates. She is the second woman ever elected to a leadership position in the Labour Party.
According to a BBC analysis, "Harriet Harman's election as deputy Labour leader came as a genuine surprise and has sent some pretty clear messages to Gordon Brown....
Her victory, therefore, suggests Labour members want not only a woman deputy - something she put at the centre of her campaign and which must not be understated - but also someone who had put clear distance between herself and Tony Blair."
"The voting system always had the potential to produce a surprise and, it has to be said, her team were warning right until the end that the contest would not be as clear cut a run-off between Alan Johnson and Hilary Benn as many had been predicting.
The breakdown of the vote, which went to five rounds, showed her being the most popular contender among Labour members and second most popular among the party's MPs and MEPs.
She was only fifth in terms of being the first choice of union members - although it was the second choices of those who backed Jon Cruddas (including many union members) which meant she overtook Alan Johnson in that last round."