Amy Winehouse’s mother has pleaded with Boris Johnson to make urgent changes to the benefits system to end the “disgusting” treatment of disabled applicants.

Janis Winehouse delivered a 21,000-signature-strong petition to Downing Street with campaigners who are demanding action from the Prime Minister.

They are calling on Mr Johnson to fix the process for claiming Personal Independence Payments (PIP).

The benefit, which replaces the Disability Living Allowance, is designed to help with the extra costs of a long-term health condition or disability.

But there are concerns about the assessment process and the complexity of claims forms.

Ms Winehouse, who has secondary progressive multiple sclerosis, joined MS staff, MPs and others living with the condition to deliver the petition.

The late singer’s mother, who is an MS Society ambassador, said she wanted to “support the people living with MS whose voices still aren’t being heard”.

She added: “Some of my closest friends have been through the exhausting and demoralising process of claiming PIP, and it can’t go on any longer.

“MS is relentless, painful and disabling, and right now PIP is costing many people their independence rather than giving it to them.”

After handing over the petition on her 65th birthday, she blasted how “disgusting it is” that applicants are interviewed by people “with no knowledge of the condition”.

While she has not personally had difficulties with PIP, she said friends have seen “absolute horrors”.

Asked what she would say to the PM, Ms Winehouse said: “Please help us – get the health minister to listen and understand what we are saying.”

The campaigners were briefly forced to move out of the road in Downing Street when Health Secretary Matt Hancock was driven out in a Range Rover from No 10.

“We would’ve liked the opportunity to discuss it with him,” she said, but acknowledged that Mr Hancock has work to do elsewhere.

A Department of Work and Pensions spokesman defended the payments, saying the Government is spending £84 million more yearly on PIP and DLA compared to a decade ago.

“We will do more to help PIP claimants by introducing a minimum reassessment period and we’ve scrapped unnecessary reviews for pensioners and those with the highest needs,” he added.

“Our planned Green Paper will go further as we continue to improve the experience for people with long-term health conditions and disabilities.”

But veterinary nurse Ashley Arundale, 29, from Leeds, has the relapsing form of MS and said the PIP process is “designed to trip us up at every turn”.

She said: “I don’t feel my assessor understood MS at all, and she gave me no chance to explain the condition. When I eventually got the report it was full of contradictions, and ignored anything I’d said that was inconvenient to her version of me.

“I’m not an angry person but it makes me really angry – the total lack of knowledge was alarming. I thought about appealing but was afraid of making a fuss and losing the award altogether, which I know has happened to others. Right now I don’t feel supported by the system at all.”

Jonathan Blades, head of campaigns and external relations at the MS Society, added: “The UK’s welfare system is in crisis, leaving thousands of disabled people suffering as a result.

“A process that was designed to protect society’s most vulnerable is now too often doing the opposite.

“We hope the Prime Minister will read this letter carefully, and understand the impact these deeply flawed assessments are having. It’s about time we had a benefits process people can trust.”