The wife of a Bucks man due to end his life at a Dignitas clinic in Switzerland said his final weeks have been marred by police inquiries into her involvement in his plans.

Geoff Whaley, 80, of Chalfont St Peter, has arranged to end his life today (Thursday) to avoid a protracted death from motor neurone disease, which he was diagnosed with two years ago.

His wife Ann, 76, had supported his decision, but found herself being interviewed under caution by Thames Valley Police after someone made an anonymous call to social services.

Helping someone commit suicide is punishable by up to 14 years in prison.

Mrs Whaley booked the flights to Switzerland and a hotel because her husband can no longer use his hands.

In an interview with the Times, Mr Whaley, a former accountant, said: "I really wanted a quiet few weeks to reflect on what is happening and that's when the bomb dropped."

He said the added stress of police involvement had "destroyed everything we had done to prepare ourselves".

Mrs Whaley said: "In 52 years of married life, Geoff has never cried, but that day, he put his head down and sobbed. That made me very angry.

"I wasn't frightened because I didn't feel like I'd done anything wrong. I wasn't ashamed. I was cross.

"My whole attitude throughout Geoffrey's illness is that I'm here to protect him from all the slings and arrows from the outside world so that he can enjoy the time he's here.

"It was so ridiculous to put us through this when he is in the final few days of life."

Police have since dropped the case, but the couple - who have two adopted children and four grandchildren - want to see the law changed to allow assisted dying in some circumstances.

They believe the law can be written to ensure vulnerable people are still protected from abuse.

At least three Britons have faced a police investigation after returning from a loved one's assisted death at a Dignitas clinic, the Times reported, although no-one has been prosecuted.

When asked if he is concerned about the consequences his wife could face, Mr Whaley replied: "Ann can handle anything.

"The one thing that has worried me all along is leaving Ann because I've spent all my life protecting her. Now she'll be without me, but I know she'll get through it."

As Mr Whaley prepares to end his life, he has written an open letter to MPs to urge them to change the law on assisted dying.

He writes: “By the time you read this, I will be dead. With [my family’s] love and support I have been able to fulfil my final wish: to be in control of my end, rather than endure the immense suffering motor neurone disease had in store for me.

“I want to impress upon you the anguish me and my family have experienced, not because of this awful illness… but because of the law against assisted dying in this country.

"The blanket ban on assisted dying has not only forced me to spend thousands of pounds and endure months of logistical hurdles in order to secure a peaceful and dignified death overseas, but it has meant that my final weeks of life have been blighted by visits from social services and police.”