DOCTOR WHO IN DETAIL

When the Doctor first met Harriet Jones she was the MP for Flydale North, caught up in the Slitheens' attempt to destroy and sell Earth. She was in Downing Street trying to push for Cottage Hospitals when the an alien spaceship crashed in the Thames. She was possibly the most senior minister to survive the Slitheen encounter and later became the Prime Minister.

The next meeting was during the Sycorax invasion. With the Doctor recovering from his regeneration Harriet did what she thought was needed to protect Earth, and asked Torchwood to destroy the Sycorax. Despite the Doctor's protests, Harriet gave the order to destroy the Sycroax as they retreated after the Doctor gave them a warning. The Doctor then spread a rumour that Harriet Jones was looking tired, and this led to her being replaced as the Prime Minister.

Harriet Jones, away from public office and knowing that one day Earth would be in danger without the Doctor to help, helped to develop the Subwave Network. Using the Subwave Network she was able to help Torchwood, Martha Jones and Sarah Jane Smith communicate during the Daleks' attempt to destroy. In order to allow Torchwood to send a boosted signal to find the Doctor she allowed the Daleks to find, and exterminate, her.

Harriet Jones always introduced herself whenever she met people. Being a public figure usually people, and the Daleks, replied with "I know who you are".