Film about a woman with dementia and her son. What is it called?

It's a British one off pogramme, about an elderly woman and her son. It's starts after the woman has died, and the son is looking around his Mothers house reminiscing and then the film goes back to the memories and the events leading up to his Mother's dementia, her subsequently going into a nursing home and her death. It was heartbreaking and I would really like to see it again.