Regarding the Hitler Paintings that were sold in Lostwithiel Cornwall
yesterday, is there any way of finding out the identities of the
people who brought the paintings, and more importantly, to find out
where exactly in Belgium they came from?

Even if there is ... personal information may not be disclosed on this site.

This is a very relevant article:

Paintings Said to Be Done by Hitler Sold
http://abcnews.go.com/International/wireStory?id=2493454
...be sure to read the fine print under the image of one of the paintings.

Yes, all the sites about the auction say that the seller wanted to
remain anonymous, an older lady in Belgium who found the suitcase with
the paintings in her attic.  It is stated that the paper was analysed
to have dated from the appropriate period, but one site explains that
this was done in 1986 and that the persons involved have passed away,
so that their work cannot be traced.
This may be true, but it would seem that the analysis could easily be
duplicated, which to me suggests a reluctance to do so.

Its very easy to get hold of old art paper but old paints are much more difficult

The ABC News article includes the following quote:

"It's in very bad taste," said Rhonda Barad with the Los Angeles-based
Simon Wiesenthal Center, a Jewish advocacy group. "Most auction houses
have steered clear of such sales because it offends a lot of people
still alive today."

   I just have to wonder, does it offend anyone not alive today?