The Speaker ‘puts the question’ at the end of a debate. MPs shout “Aye” or “No” and the Speaker says “I think the Ayes (or Noes) have it”. If this judgement is challenged by further shouts of “No” (or “Aye”), the Speaker calls a division, saying “Clear the lobby”.
The division bells ring and the annunciators display a green bell.
The doorkeepers lock the exit doors to the lobbies.
Four tellers (often whips) are appointed to count the votes (one from the Ayes and one from the Noes for each lobby).
Two minutes after first putting the question, the Speaker puts the question again (meaning the Speaker repeats the phrase “The question is that…”). If the Speaker’s judgement on the outcome is not challenged (or if there are not enough tellers), the division is called off. If two tellers can’t be found for one side, the question is decided in favour of the other. Otherwise the Speaker announces the names of the tellers. Once they’re in place, the exit doors from the lobbies are opened and MPs begin to pass out of the lobbies.
MPs record their names by tapping their pass against one of the pass readers in the lobbies. The two tellers for each lobby record the number of those voting.
Eight minutes after the question was first put, the Speaker orders the doorkeepers to lock the entrances to the lobbies. You can’t get in to vote after that.
Divisions end with the declaration, usually by a whip, of “All out” to the tellers in each lobby, meaning there are no MPs still in the lobby waiting to vote. If there’s a delay, the Speaker may ask the Serjeant at Arms to investigate.
The tellers report the results to a clerk sitting in front of the Speaker in the Chamber. When the tellers from both lobbies have reported the results, a teller from the winning side announces the result to the House. The Speaker repeats the result and instructs the doorkeepers to unlock the doors to the lobbies.