A spokesman for William Hill said:
"Following the tragic events in Camden on Monday evening, William Hill is extending full co-operation to the authorities as they seek to understand the circumstances leading to this deeply regrettable and unforeseen accident.
We would like to express our sincere condolences and sympathy to the family for their loss."
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The Tooting MP has been the frontrunner in the counting process ahead of Tory challenger Zac Goldsmith.
It's not just London where elections have been taking place today. There were council elections taking place across the home counties.
A list of results for London Mayor and the London Assembly