The Labour MP behind the assisted dying Bill has described her meeting with the Archbishop of Canterbury – who warned of a “slippery slope” if it is legalised – as “good and productive”.

Kim Leadbeater and Justin Welby met on Monday alongside the Bishop of London, Dame Sarah Mullally.

Mr Welby said last week that he believed in every other place where it has been legalised, assisted dying “has led to a slippery slope”.

Ms Leadbeater has previously rejected this argument, saying her legislation would have “very clear criteria, safeguards and protections”.

The Bishop of London Sarah Mullally and Archbishop of Canterbury Justin Welby (Jonathan Brady/PA)

Following Monday’s meeting at Lambeth Palace, a spokesperson for Ms Leadbeater told the PA news agency it had been “good and productive”.

It is understood it was agreed that no other details of the meeting would be publicised.

Separately, Dame Sarah has written to clergy to warn legalisation could lead to “unintended consequences” for the most vulnerable in society.

But the bishop, who sits in the House of Lords, acknowledged clergy might have different views “for deeply personal reasons as well as theological convictions”.

She said she believed a change in the law would “widen the existing health inequalities which are such a scar on our national life”.

Dame Sarah acknowledged the conversation is “deeply complex” and said there is no clear religious or secular view overall.

She noted the Church of England’s General Synod – known as the church’s parliament – has voted twice in 2012 and 2022 “with a significant majority” against legalisation.

She told clergy: “I realise that for deeply personal reasons as well as theological convictions we will stand in different places in this debate.

“My prayers are with you as you reflect and pray, have conversations with those in your pastoral care who want to talk about these issues, and decide whether to write to your Member of Parliament on the matter.”

The former archbishop of Canterbury, Lord Carey, has been a long-time supporter of change and previously said it was his “greatest hope that, after many years of delay, lawmakers will now finally grasp this issue and craft a new settlement for dying people that provides the compassion and kindness that so many in this country would like to see”.

He told the Guardian earlier this month that “church leaders have often shamefully resisted change” as he urged them: “Let’s not follow that trend.”

Former archbishop of Canterbury Lord Carey has spoken out in favour of assisted dying (PA)

In her letter, Dame Sarah said she believed the debate on what she described as “assisted suicide” is important but insisted being ready to decide on a legal change is another matter.

She said: “As chair of the UK Commission on Bereavement I have encouraged us as a nation to talk about death. The debate on assisted suicide is an important debate to have.

“But we are a long way from being ready for a fully informed debate and even further from being equipped to decide on a change in legislation.”

Ms Leadbeater’s Terminally Ill Adults (End of Life) Bill was formally introduced to Parliament last week and is due to be debated and possibly voted on for the first time at the end of next month.

The precise detail of the proposed legislation – setting out the circumstances which could lead someone to be eligible – is unlikely to be published until closer to the November 29 debate.

But Ms Leadbeater has indicated she would like to see a “time frame” on the diagnosis of patients, and she has said there must be both medical and judicial safeguarding when it was put to her that the Bill could require two medical professionals and a judge to agree.

Labour MP Kim Leadbeater presented her Bill to Parliament on October 16 (House of Commons/UK Parliament/PA)

She has also said there is “absolutely no question of disabled people or those with mental illness who are not terminally ill being pressured to end their lives” and argued any new law would not come into effect as an alternative to good palliative care.

Dame Sarah, who was a nurse, said her view has been informed by her time working in healthcare as well as her religious beliefs.

She wrote: “My own approach is not just underpinned by my faith, but also my time as a nurse, especially caring for those who were dying. There are many who die well. As dying is part of living, there is often life to be lived during this time.

“It is clear that we have not invested in palliative care or palliative care research, and that to do so would make a profound difference to people’s experience at this point in their lives.

“We also need to guard against unintended consequences. Giving choice to some will take choice away from others, especially the most vulnerable in our society: the elderly, those living in poverty, those who are at risk because they are disabled, and those in coercive relationships.

“It will widen the existing health inequalities which are such a scar on our national life.”

Catholic leader the Archbishop of Westminster, voicing his opposition to a change in the law, has said suffering “is an intrinsic part of our human journey”.

In the letter to be read out in the churches of his diocese, Cardinal Vincent Nichols said: “He (God) brings our humanity to its full glory precisely through the gateway of suffering and death.”

He also warned that changing the law could result in those who are near to death feeling pressured to end their lives to relieve family members of a “perceived burden of care”, to avoid pain or “for the sake of inheritance”.