Thanks for the links @DHowett but …hmm.
My experience is, as I noted, that Windows has a problem with TPM and asks me to reestablish authority. The issue, according to the Windows error message, is an incorrectly configured TPM (Windows recognises TPM’s presence but finds its configuration unacceptable).
So, I head back into the Bios setup, “Enable” TPM Operation, and Windows is happy again … for a while anyway.
How do I resolve this?