Exclusive: On eve of Commons vote, MP says legislators may not get another chance to ‘do the right thing’ for 10 years

The UK is “behind the curve” on assisted dying among progressive nations, the bill’s sponsor Kim Leadbeater has said on the eve of one of the most consequential votes for social change in England and Wales.

The Labour MP told the Guardian that the circumstances may never be right again to pass such a bill, which would legalise assisted dying in England and Wales for those terminally ill with less than six months to live, subject to approval by two doctors and a panel of experts.

Her intervention came amid more warnings about the safeguards in the bill, including from the Royal College of Psychiatrists and disability activists – who will protest outside parliament on Friday at the final vote in the Commons.

Opponents believe the bill will not sufficiently protect those with mental illness or disability or from coercion by abusers. On Thursday, another leading Labour MP, Dan Carden, told the Guardian he would vote against the bill and the Conservative leader, Kemi Badenoch, urged her MPs to oppose it.