Emma is a young woman living in York who needs a permanent catheter to empty her bladder. A temporary operation at Pinderfields hospital to stimulate her sacral nerve greatly improved her condition, but her consultant’s request to fund a permanent operation to reduce the need for a catheter has been turned down.

I wrote on Emma’s behalf to the Vale of York Clinical Commissioning Group, but was told that this is a specialised decision which will be made by NHS England. I am still waiting to hear back from them.

Emma’s consultant has said the cost of permanent catheterisation - including the cost of hospital admissions each time she gets a urinary tract infection - will be much greater than the cost of the operation to improve her condition.

This is just one example of somebody living in York who cannot get the treatment their doctor recommends. I have been contacted by a growing number of constituents who cannot get treatment on the NHS, even though patients in other areas are still being treated.

This is why I introduced a National Health Service (Right to Treatment) Bill in the House of Commons last month. The Bill seeks to do three things:

• To ensure that any medical treatment prescribed by a doctor will be provided by the NHS unless the Secretary of State for Health, or his medical and scientific advisers at the National Institute for Health and Clinical Excellence, say no.

• To establish a national register of all cases where treatment is refused to promote more consistent provision of NHS services, and to act as a check on creeping privatisation.

• To give patients a right of appeal to an independent tribunal if treatment is denied.

I believe the NHS should provide equal access to treatment, when prescribed as necessary by a doctor or other qualified clinician, to NHS patients wherever they live. NHS expenditure per person is down in real terms from £2,043 in 2009-10, to £1,999 this year and is due to fall again next year to £1,986, according to figures prepared for me by the statisticians in the House of Commons Library.

In 2012 and again last month I asked parliamentary questions about the number of funding requests that are turned down, but I was told that the data is not collected centrally. I therefore carried out my own survey in 2012 of all the Primary Care Trusts in England to find out how frequently they refuse to pay for treatments recommended by NHS doctors for their patients. 72% of PCTs (109) replied.

The number of Individual Funding Request (IFR) approvals in 2009-10 was 51,661. The number of approvals in 2011-12 had fallen almost by half to 26,076. There is also enormous variation in approval rates. In 2011-12, 10 out of 109 PCTs approved 75% or more of IFRs, while seven PCTs approved 25% or fewer.

The survey revealed enormous variation in NHS provision across the country. Infertile couples in York have no access to assisted conception services, but these treatments remain available free on the NHS elsewhere.

Gastric band surgery is generally available to people whose body mass index is 40 or more, but in York you have to be much more overweight, with a BMI over 50, to get this operation. York’s NHS budget is lower per person than in neighbouring health areas, which makes a bad situation worse.

The postcode lottery is unfair. It contradicts the founding principles of the NHS. We all pay national insurance and taxes on the same terms, no matter where we live, and we should all have a right to NHS treatment on equal terms. Each time the NHS says no to a patient a little more public confidence in the NHS drains away. This needs to change, and quickly.