Edward VII's "German accent"

There seems to be a consistent tradition that King Edward VII of the
United Kingdom spoke with what some contemporaries considered to be a
"German accent". The characterization of this accent varies from
"slight" to "marked" to "heavy".

It's not at all clear, however, what aspects of the King's
pronunciation struck contemporaries as "German", and to the best of my
knowledge, no recordings of his voice survive.

This "accent" was sometimes attributed to his upbringing by a Coburg
father and a half-Coburg mother, as well as early fluency in German.
However, these explanations seem to me to be inadequate.

First, upper-class Victorian parents were less intimately involved in
the upbringing of their children than modern parents usually are, and
there's no indication that Victoria and Albert were exceptional in
that regard. Albert Edward's early education, as Prince of Wales, was
at the hands (and voice) of Sarah, Lady Lyttelton, who was totally
English, until the age of seven; he then passed into the hands of the
equally English Rev. Henry Birch, and then a Mr. Frederick Gibbs. His
ideas, whether unconsciously learned or explicitly taught, of how
English should be spoken must have been derived from these teachers
and tutors, with whom he spent the greatest part of his time, and not
from his father and mother.

Second, to the best of my knowledge, the other children of Victoria
and Albert did not speak with a peculiar accent. (Do recordings of any
of their voices survive?)

The difficulty of explaining Albert Edward's accent by reference to
his parents suggests that some other explanation should be sought.
Could it be that the accent was not natural, but was a _deliberate_
affectation on the Prince's part? But if so, whom was he imitating,
and what was his purpose? Or could it be that he had a slight speech
impediment -- for instance, trouble articulating his r's -- which his
contemporaries were pleased (either by error or by way of whitewashing
the problem) to characterize as a German accent?