Rosena Allin-Khan, the new MP for Tooting, paid an emotional tribute to tragic Jo Cox after she was elected to replace Sadiq Khan in the seat.
Mrs Cox was killed outside her constituency surgery in West Yorkshire just hours before the by-election result was due to be announced.
The news rocked the nation and the count in Tooting had a sombre tone in light of the event.
Dr Allin-Khan won the election, increasing Labour’s majority in the seat.
In a statement made after the announcement, she said: “First of all, I would like to give my profound thanks to the people of Tooting for electing me as their MP.
“But my thoughts and prayers are with Jo’s husband and her children. She was a proud and passionate campaigner who will be desperately missed.
“Jo’s death reminds us that our democracy is precious but fragile – we must never forget to cherish it. Thousands of people voted today and we are all here in recognition of our democratic values.
“I would like to thank the police for all the hard work they have done today, not just here but across the country.
“I would like to thank the returning officer and staff for their efficient and smooth running of this by-election, and I would also like to thank my agent and his campaign staff.
“I would like to thank the other candidates for the respectful way in which this by-election has been fought.
“And lastly, I would like to thank my family and friends for their love and support.”
At 11pm, the count fell silent for two minutes in tribute to Mrs Cox.
The Mayor of Wandsworth, Councillor Richard Field, said: “As the returning officer, I want to express the sadness everyone involved in this by-election has felt today at the dreadful death of Jo Cox and to convey our deep felt condolences to those closest to her.
“The impact of this tragic event is being felt right across the country, but it has a very deep resonance here in this room, as the votes are counted for Tooting’s new member of parliament.
“With this in mind, I request that we hold a two minute silence in tribute to Jo Cox – please observe this with me now.”
Candidates remarked through the evening that the tone was sombre given the tragic events of that afternoon.
There were fewer cheers when the polling numbers were announced and Bobby Smith, who usually hears the votes announced in an Elmo costume, refrained from wearing it on stage.