London Mayor Boris Johnson was on a business trip in Hong Kong last week. He hopes to sell the new London Route Master bus to the Chinese.
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The owners of Holloway Cycles have run the shop for seven years, but struggled against increasing competition.
Dressed in a hat and dark glasses, the singer and former X Factor judge seemed to travel around the Tube network completely unnoticed.
Ambulance chiefs said anyone with a long-term or chronic illness who feels unwell on Thursday should try to ensure they are not alone.