The NHS is relying more on charities - and that might be creating problems for patients

There's nothing new about UK health charities taking on a major role in delivering services. Prior to 1948, British healthcare was provided through a patchwork of local charities, voluntary organisations, local authorities and private arrangements. Many hospitals depended on charitable donations, subscriptions and fundraising events to survive.

The creation of the NHS transformed this model. Most hospitals were brought into public ownership and funded through taxation. NHS founder Aneurin Bevan believed healthcare should not depend on charity, and restrictions were placed on NHS hospital charities actively raising money. But they did not disappear completely - they could still receive gifts and donations.

A major shift came with the Health Services Act 1980, which encouraged a more active fundraising culture. From then on, NHS charities expanded significantly and became increasingly professionalised. By the 1990s and beyond, they were raising substantial sums for equipment, buildings, research, and the likes of play areas in children's wards and well-equipped staff rooms.

Today, distinct from charities devoted to particular diseases or conditions, there are now more than 220 NHS charities attached to hospitals or community services, which raise £620m a year.

Ellie Orton, chief executive of NHS Charities Together, which represents them, says that while this sum may sound high, it represents only around 0.3% of the health budget.

She says the very purpose of the charities is to provide support, equipment and services that are additional to what the NHS provides. Recent schemes involve things like CPR training for members of the public, defibrillators being placed in community venues and green spaces in hospitals.

But it is a fine line. Scanners, blood transfusion equipment and emergency department co-ordinators have also been funded by charities. Some would say say core NHS functions like these are exactly what we pay our taxes for.

Orton defends this. "It's just the way it is now. We shouldn't get too ideological about this. It's not helpful to think the state can do everything. Yes we pay taxes but that has to cover lots – and it's finite. If our fund-raising means a parent of an ill child can stay close to their child while they are in hospital in a room funded by a charity, why not?"

The legislation change in the 1980s, coupled with the market reforms of the 1990s, also helped pave the way for specialist disease-specific charities such as Macmillan, Marie Curie and Dementia UK to get involved in the delivery of NHS services.

For example, over the past three decades, Dementia UK has developed a well-established network of specialist dementia nurses known as Admiral Nurses, who work in a range of hospital and community settings. The model is based on the charity co-funding posts with the NHS for up to two years with the expectation that the NHS will then take on the funding.

But with demand increasing, Edwards says it is becoming a "struggle" to get the funding needed from the NHS or from donations. "We are being asked to fund them for longer or find more than half the cost," he says. "Services are really being cut back."

And it is not just in dementia care that charities are noticing a squeeze. The charity WellChild has helped establish a network of 54 specialist nurses who work with very sick children. It funds these posts for the first three years, before responsibility for funding is expected to transfer to the NHS.

But disappointingly for the charity, for the first time this year a nurse post was not kept on, says Amy Mitchell, WellChild's director of programmes. What's more, WellChild's nurses are only meant to carry a caseloads of 15, but the average is currently 40. "Services are being dismantled - and our nurses are propping things up," Mitchell adds.

Others in the voluntary sector agree. Charities are increasingly being asked to do more with less, says Mark Yates, chief operating officer of Rethink Mental Illness, "and there is too often an expectation that we will absorb shortfalls ourselves to keep essential services running".

Parkinson's UK told the BBC its funding has helped the NHS pay for around 70% of the specialist nurses working in the field - and its chief executive officer Caroline Rassell says it's unfair on people affected by the disease.

"Charities having to fund these posts is effectively an additional 'tax' on people with Parkinson's as they are our main donors," says Rassell. "Nursing care should be the cornerstone of what the NHS offers."