Emma Watson is leaving books on the Tube with secret notes written in them

Just when you thought she couldn't get any cooler, Emma Watson spent the day leaving feminist literature on the Tube.

As part of the Books on the Underground initiative, which since 2012 has had 'book fairies' place novels around the London Underground to encourage commuters to read: about 150 each week.

The Harry Potter actress left about 100 copies of her chosen novel, with personalised messages inside.

100 copies, for 400 million commuters to fight over.

Watson, who is also the UN Women Goodwill Ambassador, recently began a feminist book club Our Shared Shelf: an open group which holds meetings and discussions through Goodreads.

The novel she left out today was this month's choice: Mom & Me & Mom, the seventh and final autobiographical installment from the great, late poet Maya Angelou.

People are pretty excited about Watson's latest venture...