I am writing to you as a matter of urgency, regarding a vital procedure I have been waiting to receive for two years, and that had finally been scheduled for the [date], which has now been cancelled.
The reason given for the cancellation of the critical [procedure] I require, and have required for the last two years, is that I intimated to the hospital that I did not wish to receive a test for the COVID-19 virus.
I have attempted to correspond with junior hospital staff about this issue previously, but have received only cursory brush-offs and dismissals, and the urgent nature of this matter means I am now taking it up with senior management, as well as the local NHS Trust, who are receiving a copy of this letter.
As you are aware, the NHS is governed by strict guidelines of informed consent, as per the Montgomery ruling , as prescribed by the General Medical Council. The GMC makes it abundantly clear to all medical practitioners operating under its banner that informed patient consent is critical for all medical processes, and that consent must be offered freely, based on adequate information, and in the absence of any form of coercion.
Clearly, withdrawing my urgent medical care from me if I do not submit to testing is coercive in the extreme, therefore in breach of all medical ethics law, as well as multiple international treaties on human rights. UNESCO's Universal Declaration on Bioethics and Human Rights states at Article 6, section 1:
"Any preventive, diagnostic and therapeutic medical intervention is only to be carried out with the prior, free and informed consent of the person concerned, based on adequate information. The consent should, where appropriate, be express and may be withdrawn by the person concerned at any time and for any reason without disadvantage or prejudice." 
These rights are enshrined in law and cannot be invalidated or overridden by internal "policies" of hospitals, regardless of what colour flags these hospitals decide to attach to themselves. I have been informed by administrative staff at your institution that hospitals now consider themselves either "green flag" (where they will treat patients who have not been Covid tested) or "red flag" (where they will not). However, such policies have no basis in law and are simply internal preferences. They cannot and do not invalidate robust and well-established human rights' laws.
To be clear: I have a legal and ethical right to receive my urgent medical treatment without suffering penalty, discrimination or (further) delay in the absence of testing for COVID-19.
Although the law places no obligation on me to provide you with reasons for my declination, I will do so for your interest and to help better inform your "policies" moving forward.
In the first instance, neither the PCR nor lateral flow tests are reliable indicators of the presence of infectious viral illness.
The PCR test's own inventor, Nobel-prize winning scientist, Kary B. Mullis, stated that his test must never be used as a reliable diagnostic for the presence of viral disease. "PCR tests cannot detect free infectious viruses at all", Mullis said .
The unreliability and concomitant dangers of the PCR were starkly illustrated in the USA in 2007, when a pertussis epidemic was falsely declared on the basis of PCR testing . Nearly a year later, the entire episode was declared a false alarm, since not a single case of pertussis was confirmed with the definitive test, growing the bacterium, Bordetella pertussis, in the laboratory. Instead, it appears the individuals who tested positive on the PCR were probably afflicted with ordinary respiratory diseases like the common cold. According to epidemiologists and infectious disease specialists, this episode occurred because too much faith was placed in a quick and highly sensitive molecular test - the PCR test - that led them astray.
Reflecting on the situation, Dr. Cathy A. Petti, an infectious disease specialist at the University of Utah, said the story had one clear lesson.
"The big message is that every lab is vulnerable to having false positives," Dr. Petti said. "No single test result is absolute and that is even more important with a test result based on PCR." 
It is critical that the hospital management understands the mechanism by which PCR tests operate, which is to amplify results many times. If results are amplified less than about 35 times, no-one will test positive. If they are amplified 60 times, everyone will. As the PCR test's inventor, Mr. Mullis, clarified: "With the PCR, you can find almost anything in anybody. It doesn't tell you that you're sick." 
Moving on to the lateral flow test: The Guardian newspaper issued a report earlier this year warning of the dangers and inadequacies of the lateral flow test. According to The Guardian, lateral flow devices are "inaccurate and may cause more harm than good" (5). The newspaper quotes Professor J. Deeks of Birmingham University and the Royal Statistical Society, and colleagues, who have stated in the British Medical Journal:
"The UK government is widening the rollout of the Innova lateral flow test without supporting evidence, and we understand that this may soon extend to further home use. This may cause serious harm. We call on the government urgently to change course.” (6)
Many other experts harbour deep reservations about these tests, with Clinical Professor of Public Health, Allyson Pollock of Newcastle University, stating in the New Scientist that mass screening using lateral flow tests should not have been widely introduced before being tested for accuracy in the community. Pollock states: “[Lateral flow tests] have not been evaluated outside of a laboratory setting.” (7)
Further compounding my concerns about both PCR and lateral flow testing is the method by which the tests are administered. The insertion of a swab far up the nasal cavity is an extremely invasive experience, the thought of which not only causes me significant anxiety and distress, but which is documented to be potentially dangerous. Media reports have detailed cases of the nasal swab penetrating the blood-brain barrier and causing brain fluid to leak (8), and there are also reports of the swabs being contaminated due to inadequate quality controls (9)
I hope this makes it abundantly clear to you that my decision to decline COVID-19 testing is based on adequate information, and I hope you will use these facts to inform your hospital policy moving forward.
Please reply to this letter as a matter of urgency, confirming that my decision to decline COVID-19 testing will be respected, and that there will be no further delays to my receiving my already very delayed medical care.