Petronella Osgood

Osgood was a scientist who worked for UNIT when Kate Stewart was in charge. On the Eleventh Doctor's orders, she analysed the stone dust in the undergallery under the National Gallery. The Doctor also took a liking to her large scarf, which was strikingly similar to one he wore in his fourth incarnation. She was asthmatic, and often forgot to use her inhaler when she needed to, especially when over-excited. The Zygon who took her form disliked this and was annoyed at "getting one with a defect," and promptly took her inhaler. She had a sister which the Zygon made a comment on which suggested Osgood often compared herself to in a negative way(TV: The Day of the Doctor).