Mrs May also told the court that she had not been keen on Matthew's relationship with Hoare, and thought she was "much too young" for him. The court heard the couple had got together when Hoare was 15 and when Matthews was 21.
She said she had noticed a visible change in her grandson when the pair started dating.
He definitely changed when they were together.
He became less interested in his appearance, he stopped working so he could spend all his time with Shauna, and generally he didn't seem very happy.
Mrs May also told the court that Matthews had been very involved in the Territorial Army before he met Hoare, but as soon as the pair got together he stopped going altogether.
Something, Mrs May said, she "never really understood why".
Shauna, in a lot of ways, was more dominant. She very often told him what to do, to change things and that. The way she seemed was quite dominant, like the way she spoke to him.
I believe Nathan tried to control Shauna, and she would always get her own way and get what she wanted.
The court heard Matthew's had become "almost paranoid" and "noticeably different" in the last couple of years.
http://www.itv.com/news/west/story/2015-10-19/becky-watts-trial-day-10/