London Zoo says it believes Melati carried the cub outside, but keepers are unclear as to how the cub got into the pool.
Keepers are now reviewing the situation because it was not forseen that the mother would take the cub outside so early.
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Showers around this evening and overnight - keeping the temperature fairly mild, but not feeling pleasant.
The rapper answered questions in a live Q and A on YouTube.
The candidates from the Tory, Labour, Green and Liberal Democrat parties have backed calls to have Oxford Street vehicle free.