Speaking to ITV News ahead of tonight's switch on in Oxford Street, Jessie J said Christmas helped put London in a good mood - which was what the capital sometimes needed.
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The two victims died from their injuries in hospital after the explosion in Hertfordshire.
Investigations are continuing into the cause of the crash in chigwell which killed both people on board.
Residents of a Kent estate are furious with a housing association for charging them £400 a year to park in their own street.