Gracie Brooks is a woman with a Cockney accent and rough clothes, evidently from a poorer part of town. She first appears when Higgins informs Crabtree that his mother is waiting. Needless to say, Crabtree is quite confused with his two "mothers," and his unable to prove one or the other as his real one.
As the women meet, fire meets fire as they literally fight over George, interrupting his police work. In desperation, Murdoch creates a ruse to help solve the case and Crabtree's conundrum, pretending the officer was shot. Julia Ogden meets with the mothers, who trades barbs, and harshly tells them that whichever one of them is fake can leave, as George no longer has his job, pension, or standing as a police officer. When George opens his eyes, it's Gracie by his side.
When George asks why she gave him away, Gracie admits she was trying to do the right thing and give him the best chance in life. She hadn't wanted to give him up, but chose to sacrifice her wants for the sake of George's future. They are both grateful that they met one another again, and Gracie is proud of the man George has become.