The charity analysed polling from the research company YouGov and estimated that around 23,936 people were forced onto an electric prepayment meter against their wishes, with around 12,000 forced onto a prepayment meter for gas.

Companies have also used a ‘back door’ approach, but switching smart meters into pay-as-you-go meters. In these cases around 17,952 have seen their meter changed without their consent and around 12,000 for gas.

The analysis comes following the energy regulator Ofgem giving the green light to suppliers to restart forced installations.

The charity is encouraging people to seek help from the Citizens Advice network in a variety of ways. People can visit www.cas.org.uk/worried and from there they can choose an option that works for them such as:

• Check online advice pages or interactive self-help tools like moneymap.scot
• Use specialist services like the Money Talk Team
• Find their local CAB if they feel they need one-to-one advice

Last year the average gain from energy-related advice from across the network was more than £400. Advice gains generally for those who saw a benefit was over £3,700.

A pension-aged man sought advice from his local CAB after his energy supplier switched him to a prepayment meter without warning. A billing error resulted in a significant debt. He pays £160 to £170 each fortnight to clear his debt. Servicing this debt leaves him with little money to pay for other outgoings.

A woman who received Universal Credit and Personal Independence Payment sought advice from her local CAB after her supplier informed her it had applied for a warrant to fit a prepayment meter in her home. She offered to pay towards her arrears plus monthly usage. Her supplier rejected the offer and increased her monthly bill.

CAS social justice spokesperson Emma Jackson said: “The issue of forced installations of prepayment meters shocked and horrified people last year, and this research suggests the scale of the issue. As some suppliers get the green light to resume the practice many people, especially those behind on bills and struggling with energy debt, will be worried.

“We believe that the forced installation of these meters should be banned permanently. For many people it means energy is a luxury at the start of the month, and then something they have to ration or even go without the further away they get from payday.

“Anyone who is worried about bills and money this winter should seek advice from the CAB network. For anyone on a prepayment meter struggling to top, don’t struggle alone. Advice and support is available.

“That doesn’t have to mean going to a CAB, our online advice pages are used by millions of people a year and we have interactive self-help tools to help people see where they could boost their incomes or cut their costs.

“The CAB network gets incredible results for people. Last year the average gain for someone who saw one after seeking advice was over £3,700. That can be absolutely life changing money this winter. We don’t judge, we just help.”