‘It’s hard to describe but it was a heavy, slightly musky aroma.

‘I had no idea that this was unusual and hadn’t been recognised before.’

Describing how she got in touch with the scientists, she said: ‘I was attending a Parkinson’s UK research lecture at the University of Edinburgh I mentioned it to the researcher, Dr Tilo Kunath.

‘Tilo was interested and together we worked out ways to see if I could detect it from other people with Parkinson’s and not just Les.