If they do help, it should not automatically mean they can be released, she added. She said: "I feel really elated and quite relieved that it's finally happening.

"I really can't believe it. I have been trying for so long

"It has been a terrible stress on me since I started the petition in 2015. It was voted for in Parliament but then it was delayed after the general election.

"I just know Brexit took up too much time in Parliament.

"This law will help so many other families."

When she marks what would have been her daughter's 54th birthday later this month, she said it would be with her "heart lifted" in light of the news.

But she said it was still agony being denied the chance to recover her daughter's remains, adding: "I wrote to him, begging him 'please, please just tell me and you will not hear from me again'.

"I still hope he will remain in prison until he tells me.

"I hope one day I will know."

She thanked her "amazing" MP Conor McGinn and Mr Gauke for their support in the campaign and said the wait for change was long but worth it.

Parole Board guidance already says offenders who withhold information may still pose a risk to the public and could therefore face longer in prison.

But Helen's Law will for the first time make it a legal requirement to consider this withholding of information when making a decision on whether to release an offender, the Ministry of Justice said.

It is hoped the legislation will be brought into force as soon as possible.

Courts can also hand down tougher sentences for murderers who deliberately conceal the location of a body.

Mr Gauke said: "It is a particular cruelty to deny grieving families the opportunity to lay their murdered loved one to rest and I have immense sympathy with Marie McCourt and others in her situation.

"Those responsible should know that if they choose to compound this further through their behaviour, they will be held accountable."