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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A total of 270,000 documents is expected to be submitted to the inquiry.
In September TfL refused to renew Uber's licence on the grounds of "public safety and security implications".
Lord Kerslake said the health service could not continue "staggering along" under the current funding levels.