Thank you all, I did ring the Samaritans to ask for advice at the time but they could only suggest that I made sure she was taking her medication and to get her to call them.
Years ago when I lived in the Midlands mental health patients had a designated person they could call in a time of crisis, it was a good system but probably no longer exists after so many cuts. I doubt my friend would be able face a taxi ride to A and E in her wheelchair, she is physically frail and also an uncontrolled epileptic, explaining her situation over the phone to someone without psychiatric training, especially if she is hearing voices at the time, would probably be too difficult for her. There is an emergency crisis team for our area but I couldn't find their phone number when I looked, Mind is a good idea I will ring them.