The casting vote is the vote that decides an issue when two sides have exactly the same number of votes. In the House of Commons the casting vote is held by the Speaker or the chairman of a committee. The convention is that the Speaker's casting vote always gives the House another chance to discuss the subject before any final decision is taken. In the Lords, the Lord Speaker does not have a casting vote. In the House of Lords the Lord Chancellor is entitled to vote like any other Lord but he does not hold a casting vote.
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About Parliament: divisions