Hi Stuart,    I doubt very much if they do both at the same time and it does
not matter in what part of the world you live in.  I have been in arthritis
newsgroups for many years and do not remember anyone speaking of it being
done.
Harv

Stuart, you're in Europe I believe while most of us are in the U.S. and
don't know/understand how medical procedures differ between the two.

I don't know what "long waiting lists" means to you, but I had my THR
6 weeks after consulting with the surgeon.

BUT, there has never been a participant in this group who has had
all 4 joints - 2 hips and 2 knees - replaced simutaneously.  Recovery
from THR and TKR are significantly different, and what is allowed for
one is not allowed for the other....physical therapy is totally different.
Restrictions are totally different.

Posting this now in case anyone has the same question.

Hip problems often cause referred pain in other areas, especially the
knee. If you have knee pain, it might be caused by the hip arthritis.
Therefore the proper sequence is to first repair the hip, and rehab that
for a few months. If you still have knee pain, then you treat that. I
can tell you for a fact that in my case, my knee pain went away after
getting my hip replaced.

No competent surgeon would do a knee and a hip at the same time, for
this reason.