In the immediate aftermath of the terror attack on Westminster Bridge, three miles away a major incident is declared at St Mary's Hospital, the nearest of London's four Major Trauma Centres.

Cameras follow patients at St Mary's who face a long wait, including a woman with serious mental health issues. There is also footage of patients and their loved ones coping with dementia, including a wife who is her 75-year-old husband's sole carer, and is at breaking point, partly due to his aggressive outbursts.

With access to two key specialities, cardiology and neurosurgery, staff at Imperial College Healthcare NHS Trust are pushing the boundaries of what's possible technologically, at a time when the Trust has a planned annual deficit of £41 million.