Isobel Grey, Lady Merton, (nee Turnbull, previously Crawley) is a character on the series, Downton Abbey. She was played for all six seasons by actress Penelope Wilton.
Violet's friend, crony and sometimes foil!
Isobel Crawley is a woman who involves herself in anything she deems as a good cause. She was brought up in a medical family. Her father and her brother were doctors, and she trained as a nurse during the Boer Wars. She later married a man named Reginald Crawley, who was a doctor; and with him, had a son named Matthew Crawley. After Reginald died, she and Matthew lived in Manchester, where he worked as a solicitor.
We first meet Isobel and Matthew at the end of the first episode of the series. A letter came to Matthew from Robert Crawley, the seventh Earl of Grantham, which changed their lives for good.
It turns out that Robert's closest male heirs, James Crawley and his son, Patrick had died aboard the ill-fated Titanic. This named Matthew as the next male heir presumptive of Downton Abbey, a country estate in Yorkshire.
Upon their arrival at Downton, Isobel met up with Violet Crawley, a woman who didn't much get along well with her at first, but as time progressed, they became friends, companions and cronies, although they still spat with one another on occasion!
She began working at Downton Cottage Hospital, where she would later become Almoner. She would later catch the eye of Richard Grey, the Lord Merton, who was the godfather of her later daughter in-law, Lady Mary Crawley Talbot.
Through Matthew and Mary, she is the grandmother of little George Crawley, the future 8th Earl of Grantham. George's cousins, Marigold Gregson, and Sybbie Branson, would call her Aunt Isobel, as she was their great-aunt. (Matthew was their uncle)
George would call her "Grandmamma" so Mary's mother, Cora Crawley, could be considered "Granny". Sadly, Matthew would die in an automobile accident. She would become more of a part of the family as she was George's grandmother.
Understandably, Isobel was devastated by her only son's death, and mourned her for a long while. She would later take on a motherly role in the life of Tom Branson, and he would become more of a son to him, even going to the point where he would defend her against insults by Larry Grey, by calling the rude son of her fiancé a bastard.
The final season would see Isobel and Violet at odds once more during a large fight over what could happen to the Cottage Hospital. Isobel was for the merger of the town hospital with a larger hospital in the nearby city of York, while Violet was not, more so for the reason to preserve her power over the hospital.
Cora would side with Isobel as would Richard. Dr. Clarkson, the head of the hospital, would later join Isobel's side, as he realized he wasn't thinking of the people of town. Violet would be replaced by Cora as president of the Hospital.
When it comes to Isobel's engagement, it is Violet to the RESCUE!
However, Violet's friendship for Isobel would be stronger than her anger at her over the hospital. This allowed the Dowager Countess to fight passionately for her friend when Larry, the son of Lord Merton and his snobbish wife, Amelia, would try to keep them apart.
Going on the reasoning of "When reason fails, try force!", Violet, with Isobel in tow, barged into Cavenham House and demanded that Isobel be allowed to see Lord Merton! The snobs declined, but Lord Merton came down anyway (which caused Amelia to scold her husband for letting him out of his sight!).
Isobel announced that after she talked with her fiancé's valet, they would move his things to Crawley House, where she had lived since she came to Downton. Then she would also announce that she would marry him as soon as possible. Lord Merton was delighted, Violet was pleased, and the snobs were disgusted. After that, Larry, his brother, Tim, and Amelia were never mentioned or seen again.
The newlyweds happiness was complete when it was revealed that Lord Merton did not have pernicious anemia, which was fatal; but had only iron-deficient anemia.
By the time, Lady Edith Pelham was married, she was known by everyone as Lady Merton. She was clearly happy with her life.