Met Police say Olivia is described as:
- Light skinned black female, 5ft 5 inches tall
- She has long, blond and brown plaited hair
- She was last seen wearing a dark green hooded coat, a white school polo shirt, black trousers and black shoes
- She has a mental age of five-years-old
Anyone who has seen her or who knows of her whereabouts should call police in Enfield Borough on 07825832887 or 101.
More top news
Donald Trump is to visit the UK on July 13 and hold bilateral talks with Theresa May, Britain's ambassador to the US has said.
The Football Association has announced it has received an offer to buy Wembley Stadium.
The most hotly-tipped date is July 13, following the Nato summit which the president is due to attend in Brussels on the previous days.