Just found this, actually didn't realise they had taken the paragraph out of code of practice, interesting.
Still not a definitive answer though.
"Legally, nurses are free to walk on by.
In the eyes of the law, they have no more responsibility than any other member of the public to intervene in such a situation.
Professional responsibility, however, is another matter. The NMC code of conduct used to state that nurses had a duty to intervene in a crisis wherever it happened.
‘In an emergency in or outside the work setting, you have a professional duty to provide care. The care provided would be judged against what could reasonably be expected from someone with your knowledge, skills and abilities when placed in these particular circumstances,’ it said.
But in the new code, brought in earlier this year, that crucial paragraph has been removed. Instead, it states that nurses and midwives are expected to ‘provide a high standard of practice and care at all times’ and ‘make the care of people your first concern’.
And a cautious note is sounded. As a nurse, ‘you must be able to demonstrate that you have acted in someone’s best interests if you have provided care in an emergency’. This is far less clear. Instead of a duty to intervene, it suggests a warning about the risks. "