Police say that a woman, who's believed to have given a bottle of bleach to a baby in Eltham, was wearing black trousers, black trainers, a long multi coloured top, a black jacket with white chevron type markings and was carrying maroon bag.
She has also been described as "a heavily built white female in her 50s with grey hair".
More top news
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.
If you're struggling to stick to your New Year's resolution, this could help kickstart your enthusiasm.