In the final of our three MPs’ speeches in favour of assisted dying, Vince Cable explains what prompted him to change his mind on the issue.

I thank the hon. Member for Grantham and Stamford (Nick Boles), my right hon. Friend the Member for North Norfolk (Norman Lamb) and others for giving us the opportunity to debate this subject. Members have spoken movingly and from experience about their views.​

I am someone whose views have radically changed. Until recently I was a vehement opponent of assisted dying, but I have changed my views and think I should explain why. That change is partly based on an understanding of why I was previously opposed to it, which was due to my own personal experiences. Two of those experiences were relevant, and I think they will resonate with many Members of the House.

One experience concerned my elderly mother who descended, as many do, into confusion and dementia, compounded by mental illness and depression. One week she would say, “Please, please end my life. I am a burden. I want to go”, but a few weeks later she would be enjoying the simple pleasures of life. I could see all too clearly that under a permissive system of assisted dying, people like my late mother would be extremely vulnerable.

My conviction at that time that assisted dying was the wrong route was compounded by my experience with my late wife, who contracted breast cancer and had a very long illness. She eventually died at home with good palliative care, surrounded by a loving family. She was vehemently opposed to assisted dying and wanted to live her life to the full. I guess that I took the view that that was her choice but should also be everybody’s choice.

I came to realise, however, that there are very different situations we need to understand. One thing on my conscience is that in my 20 years as an MP, two constituents came to see me to request help and political support for a campaign in the High Court to be allowed to die through assisted dying and, although I expressed sympathy, as one would expect, I declined to support their campaign. I was very wrong to do so. Both suffered from motor neurone disease, and I think many of us know of such cases. One has surfaced today: a man called Richard Selley in Perth, in Scotland, who is fighting for the right to assisted dying. I think we all know the nature of this condition. Although some people live with it, Professor Hawking being a famous example, in most cases it involves the physical degeneration of all bodily functions combined with absolute clarity of mind and very great suffering. It seems to me that we should consider the position of those living with it and similar conditions.

The argument that is deployed against doing so is that hard cases make bad law. That was quite well summarised by Lord Sumption, who gave the Reith lectures a few years ago, when he said assisted dying should be criminalised but that the criminal law should be broken. That is a somewhat strange way of putting it, but essentially what I think he was saying was that we should keep the law but turn a blind eye to exceptions and treat them compassionately.

I have thought about that argument, but it seems to me that the evidence is very strongly against it for a variety of reasons. However sensitive the Director of Public Prosecutions or the police might be—I am sure they are; the 2015 guidance is very humane—the sheer process of going through a criminal investigation and a caution is deeply traumatic, and probably the most difficult period of any person’s life. It is probably also difficult for the police who have to implement it.