You may want to redact the PCN number from the image you have provided as, together with your VRM, I was able to log into the P24 website and I could, had I been so inclined, to make your life very difficult.
As this is a Notice to Driver (NtD) from a BPA member, you should follow this advice:
Plan A: Have you gone to the hospital PALS and asked them to get this cancelled? You should also email the NHS Trust CEO and ask for their intervention in this matter.
Plan B, will be to wait until 9th of June (25 days after the NtD) and appeal, as the keeper, with the following, verbatim:
Re PCN number:
I dispute your 'parking charge', as the keeper of the vehicle. I deny any liability or contractual agreement and I will be making a complaint about your predatory conduct to your client landowner.
There will be no admissions as to who was driving and no assumptions can be drawn. Since your PCN is a vague template, I require an explanation of the allegation and your evidence. You must include a close up actual photograph of the sign you contend was at the location on the material date as well as your images of the vehicle.
If the allegation involves an alleged overstay of minutes, your evidence must include the actual grace period agreed by the landowner.
The reason for delaying the appeal is to tie them up in the appeals process at a time when they should also be posting a Notice to Keeper (NtK). Many PPCs in the BPA omit any NtK when replying to an appeal and the very fact a PPC forgets to send you a NtK by day 56, gives you a winning point at POPLA. Don't forget this tactic, and use it at POPLA stage: having appealed on day 25 or 26 after a windscreen PCN, make sure you take note of whether any postal NtK is ever received in the following weeks. A rejection letter with POPLA code is not a 'NtK'.
You must include 'no keeper liability' at POPLA stage if you do NOT receive a NtK at all in that time, and you will win as long as you make the missing NtK clear to POPLA.
Plan C is the POPLA appeal described above.