That doesn't tell a story of missing money or maintenance contracts. It tells of poor or even irresponsible and incompetent deployment procedures.
You shouldn't allow your CAT scanner to write over your patient records at a server. You shouldn't even have them in the same network segment.
So AFAICT 32-bit W10 can run most anything 32-bit XP can (likewise the 64-bit versions, though neither can run 16-bit programs), and IE11 can run most anything IE8 can (with minor configuration).
Is it software that relies on undocumented APIs? (I can't imagine why hospital software would require exotic methods of poking at the kernel or hardware).
Good luck finding a windows 10 compatible PC that has ISA slots for example. A lot of old custom hardware hooked right into the ISA bus
In my experience, industrial software is often pretty poorly designed, so it wouldn't surprise me if it's more common in a hospital environment.
We're talking about medical equipment, such as CAT scanners, dialysis machines, radiation therapy devices, chemical analysators and the like. Stuff where the computer interface could be an afterthought, added to a machine that was designed years ago with a physical knobs-and-dials type of user interface, and implemented and certified for a particular PC hardware generation. Then this interface PC becomes obsolete in 15 years even if the equipment itself would work for a hundred.
Other reasons for network connectivity include retrieving and sending image sequences and data files (basically the actual scans) which is done all day everyday.
The more alarming part is the retrieving of raw data which is the unreconstructed scan. This involves attaching a memory stick that is supposedly clean and uploading to that. Generally this stick is stuck into any old researcher PC and files are off loaded. Vendors don't particularly like this but getting 10-20 gig files off the scanner via command line is pretty clunky at the best of times.
That the NHS has not done this is their actual failing and negligence. It doesn't take that much money to move such devices to a quarantined network.