N is for... Nancy

The Doctor encountered a girl named Nancy in the East End of London during the Blitz of 1941. She exploited the air-raids to feed a group of orphaned children who lived rough in the bombed-out parts of the city. As the homeowners sheltered from the bombs, she would enter their houses and allow the children to eat their interrupted meals. 

The Doctor had first met her when she warned him not to use the TARDIS telephone. A child's voice was heard on the line - despite it not being connected to anything. Later Nancy advised him to avoid contact with a small boy wearing a gas-mask, who was prevented from joining the air-raid meals.

This despite him being her younger brother, Jamie. 

The Doctor discovered that anyone who came into physical contact with Jamie was transformed to resemble him - with a gas-mask forming part of the skull, and with the same injuries which he had sustained when caught up in a bomb blast. Later, this infection became airborne. The Doctor came to realise that Jamie wasn't Nancy's brother at all, but her son. She looked younger than she was.

A crashed alien medical ship had released nanogenes into the atmosphere and these had repaired the dead boy's body, but had no concept of what a human being ought to be like. Using him as a template, they were transforming everyone to be like him.

The Doctor was able to use Nancy, as his biological parent, to reprogramme the nanogenes and they began correcting their work. 

The Doctor and Rose were able to assure Nancy that Britain would eventually defeat the Nazis. Dr Constantine from the nearby Albion Hospital agreed to look after her and her son, after losing his own family in the Blitz.

Played by: Florence Hoath. Appearances: The Empty Child / The Doctor Dances (2005).

• An early role for Hoath was as one of the girls who photographed the Cottingley Fairies in the film Fairy Tale: A True Story. In this her father was played by Paul McGann. 
• She featured in the 2004 ITV adaptation of the Miss Marple mystery The Body in the Library along with a number of future Doctor Who guest artists.