Also, have the RAF ever flown into London City? I am thinking the A400M in medivac set up - it’s very close to Excel Nightingale if London desperately had to share the patient load with elsewhere.....
There was videos going around on social media the other week of an RAF C-130 practising landing and taking off from London City for instance:
Watching the RAF practice landings at City Airport on it’s unusually steep descent is impressive when it’s an aircraft as big as a C130.
Link (includes video)
I would imagine one of the reasons to choose the Excel to become a field hospital is its proximity to London City airport which I think can handle any RAF transport aircraft currently in service.