One thing you will find out with English shotguns and rifles
is that there ain't no rules !!!

GENERALLY, I have seen Stalking safeties on higher grade guns
but that doesn't mean they weren't put on lower grade guns -
as per my statement.

One thing we forget is that alot of DR's were ordered by people
and ordered to what they wanted - so people may have ordered
a C grade gun but specifically ordered a Stalking Safety - which
of course like all add on's, added to the overall cost.

So in answer to your question, I would say yes, they were usually
reserved for a higher grade rifles as that is where I have seen them
- except the gun referred to in this post.
..................................................................................................

Thanks Mate