The story begins in 1984 when a married woman in her 40s was referred to him, apparently suffering from a psychiatric illness.

Her ‘symptoms’ appeared when she was at home in London quietly reading a book, and a distinct voice appeared in her head.

‘Please don’t be afraid,’ the voice said in a firm but soothing tone.

‘I know it must be shocking for you to hear me speaking to you like this, but this is the easiest way I could think of. My friend and I used to work at the Great Ormond Street Hospital for Children, and we would like to help you.’

She was understandably shocked and was initially determined to dismiss the voice as a bizarre daydream. But it refused to go away and claimed that she was physically ill and would soon need help.

The voice seemed to realise it was causing her distress and said: ‘To help you see we are sincere, we would like you to check out the following…’.

The voice gave her three separate mundane pieces of information, including details of a scene unfolding at that moment outside her flat. They all proved to be true, but this failed to help because she had already decided that she’d ‘gone mad’.

In a state of panic, she went to see her doctor, who immediately referred her to the mental health unit of the Royal Free Hospital in London. Dr Azuonye concluded the woman was suffering from a mental illness and prescribed a course of anti-psychotic drugs.

The voice disappeared and she felt able to go on holiday with her husband. But the voice returned, more insistent than ever. To make matters worse, it brought along a medical colleague from the spirit world.

They told her to return to England immediately because she needed urgent medical treatment. They gave her an address to report to – the brain scan department of the Royal Free Hospital.