At least one inmate died due to poor NHS treatment. Jails are supposed to make health facilities available to inmates by having in-house medical facilities as well as allowing prisoners out of jail for critical hospital care.

But NHS figures show 197 cases were brought by inmates in the last five years where the NHS was forced to pay compensation for negligent treatment. Almost half related to prisoners who sued the NHS saying they suffered from unnecessary pain, often caused by a delay in diagnosis or a failure to prescribe the correct treatment.

Other cases included claims for physiological damage, eye problems and misdiagnosed fractures.

Over the last five years, £3.1million has been paid to inmates for NHS negligence. Another £4.4million went in fees to lawyers tasked with bringing and defending the claims.

It means the average payout to a prisoner is around £15,000, with the lawyers receiving slightly more.

In 2018, a report by the Commons health and social care committee found prisoners faced long delays in having their health concerns acted upon.

MPs said it was difficult to get help in an emergency.

And they found some inmates were denied access to medications because staff thought it would make them a target for bullying, as fellow prisoners tried to steal their prescriptions.

Often inmates have had to wait many months to see a GP, dentist or an optician.

Legal experts say the issue of medical negligence for prisoners is a complex one – as sometimes the fault can lie with the Ministry of Justice, which is responsible for running the prison, and sometimes the problems stem from poor medical treatment, in which case the NHS would be held responsible.

John O’Connell of the TaxPayers’ Alliance, said: “We shouldn’t be in a position where criminals can cash in on failings in prison healthcare.”

Neil McKinley, president of the Association of Personal Injury Lawyers said: “Losing sight, an organ or a limb will have an insurmountable impact on someone’s life. We hear all the time from people injured by medical failures that they would rather not need to claim compensation and not be harmed at all.”