Assisted dying: Arrested researcher sues Dyfed-Powys Police

Ms Tuckett told the BBC Radio 4 Today programme that she believed the police involved “had a narrative”.

“Did they really have to come to my house… in the middle of the night,” she asked, “and keep me in a cell and take all of my research materials for the best part of six or seven months”.

Dyfed-Powys Police said officers became involved when Ms Johnston was reported missing from an assisted living home.

She got someone to order her a taxi to the airport, Ms Tuckett said, and took phone calls from the police and her care home.

“She felt quite harassed by those phone calls and told multiple people, multiple times, that she was okay and she’d made her own decision.”

Police in Wales also contacted the authorities in Switzerland, she said, and Swiss officers visited Ms Johnston at Dignitas.

“So you can imagine on the eve of Sharon’s death when she should have been able to reflect on her decision and her life she was fielding calls.”

Retired NHS worker Sue Lawford from mid Wales was Ms Johnston’s assisted death chaperone and was also arrested on her return to the UK.

She has previously called the police response “aggressive”.