He said: “This time, because it’s coming from the Commons — the elected chamber — and because the Government has said that the end of this parliamentary session is not going to be until the spring of next year, we’ve got the Bill, we’ve got the approval of the Commons, and we’ve got the time. I am really optimistic that this time it will get through.”

The Express sat down with Lord Falconer of Thoroton in the office of Kim Leadbeater, the Labour MP who introduced the Bill last year after being drawn first in the ballot that allows backbenchers to propose new laws.

Ms Leadbeater admitted she had needed a break over the summer after nine intense months spent shepherding her Bill through its stages in the Commons, which culminated in a third reading vote that saw MPs back it by 314 votes in favour to 291 against.

She said: “The level of detail that has gone into producing the bill has been extremely time consuming, extremely emotional, and extremely thorough — as it should be.

“I’ve spent hours and hours with civil servants who respected the Government’s neutrality but provided huge amounts of expertise and input around the policy decisions I was making. And I’ve done dozens of sessions with doctors from other jurisdictions, we’ve consulted with different medical professions and experts.

“I did need a break over summer but equally I’ve come back now feeling re-energised to do whatever I can as the Bill’s sponsor to support Charlie, as the sponsor in the Lords, but also to support peers.”

Reflecting on the moment when the third reading vote result was announced in June, Ms Leadbeater said she felt a “huge sense of relief”.

But the Spen Valley MP added: “I don’t particularly celebrate this work because I haven’t found the cure for cancer, and I wish I had done something which meant people didn’t become terminally ill in the first place.

“It’s an extremely positive move which means a lot to significant numbers of people, but I’m also very respectful that people have different views on this subject. So for me, it’s not about celebrating. It’s about just providing the reassurance for terminally ill people.”

As the House of Lords prepares to spend further hours poring over the legislation, Ms Leadbeater has invited members to stop by her office to raise any concerns or talk through clauses they are unsure about.

She added: “I am respectful of however people choose to express their views on this issue, but what I always want is for them to be doing so based on the facts and the actual detail of the Bill.

“I think there’s a huge amount of support in the Lords. There are peers who have campaigned on the issue literally for decades. There will also be opposition of course.

“What I hope is that, with the Commons having passed the principle of assisted dying, even people who are opposed to the concept will look at how we can strengthen the Bill if they think that’s necessary.”

Lord Falconer said the norm is that the Lords would now hold a vote at a second reading, and would allow any bill backed by the Commons to progress to committee stage for thorough scrutiny.

But opponents could try to frustrate the Bill’s progress by proposing amendments that cause delays. Lord Falconer said: “It may be that some people have various procedural manoeuvres up their sleeve. I would be rather disappointed if that was the position because the Commons would expect the Lords to look at it in detail.

“Perhaps more importantly there are a lot of people who have had loved ones die in bad circumstances and a lot of people who are themselves terminally ill, who have high hopes that the Bill will get through.”

Lord Falconer said he wanted the public to see that the Lords had “looked at it on its merits and made decisions on whether it can be improved” without allowing the important legislation to be “caught in a procedural mess”.

He added: “We’ve just got to get on with it, and I think talking around the House of Lords that is very much the view, whether you’re an opponent, in favour or you have thoughts about what can be done with the bill. That’s what I think the vast majority of the Lords will do.

“I could not feel greater delight at what Kim has achieved, and anxiety that we’ve got to get through it in the Lords. I believe that we can, I’m really optimistic that we will get it through, but we’ve got to focus on making sure there’s a really good scrutiny process.”

Ms Leadbeater praised the Express’s Give Us Our Last Rights campaign for its “outstanding” coverage of assisted dying and for reflecting the views of the majority of the nation. Polling has shown around three-quarters of Britons support her proposed change in the law.

She added: “Public mood is very, very strong. I know that the Lords will be cognisant of that, and they will be very aware that the public are watching.

“As such, they will want to do a very thorough job, quite rightly, but I also think they will be aware that the public would not be particularly impressed if they were seen to frustrate this process.

“This clearly is a huge change, and I don’t underestimate that, but we’re not trailblazers on this issue. It is done safely and compassionately in other jurisdictions.”

In a message to supporters who will be watching the Bill’s progress over the coming months, the MP said they should be reassured that Parliament is “doing a really thorough job and always keeping them at the heart of the issue”.

Lord Falconer added: “There are some months to go and we have got to make sure this is the best scrutinised bill it could possibly be.

“Bear with us while we do that scrutiny but my strong, strong view is there’s going to be an assisted dying bill at the end of this process, and it’s going to be there hopefully by the time we get to halfway through next year.”