Roger: I think the declination thing was answered with the excellent photo above---thanks all---both the Suunto MC-2G and the Silva or Brunton Type 15 (Ranger) compasses have a separate clear baseplate which can be swung around by means of a tiny rack and pinion gear, accessed by a tooth-pick style screwdriver on the lanyard, such that even the terminally-tired cannot screw up the declination...works like a charm!
My delay in responding is partially because I have just carpooled 500km N. of here at 64N Tombstone Terretorial Park on a wildlife-watching tour.
Anyways, not being the trip leader, and being sleepy, I left my survival kit in my tent, and did not (gulp!) bring the Suunto with me. +5C rain, fog, 2000M above sea level, lowering clouds.
Group leaders wanted to go up, did not perceive the visibility lowering, though I pointed it out.
Ended up lingering for lunch lower down with a botanist, saw the hikers higher up get swallowed by the clouds, so laid out the bright yellow foam sitz-pad, blew the whistle, and they vectored themselves in by sound.
None had a compass, nor a GPS, none had taken a back-up bearing on the micro-wave relay tower road which was our jumping-off point. This is a trail-less, featureless tundre landscape.
I had a GPS and an Iridium Satphone, so I used the GPS to generate a back-up bearing to get us back to the tower, once they got back to me, as I was below the cloud level.
Memo to self: 'No group hikes without carrying Suunto'!! Even if I am not leading!
Yes, this is why we carry them: dial the declination in, take an insurance bearing with the mirror on your start point, close the lid, and if the fog comes down, open the lid, put the N needle in the S end to create a reciprocal (go home) bearing, use the mirror to choose a bearing marker, even use a hiker 'no, bit to the left, good, stop!', then hike to them, repeat as neccessary...
Get out on the land!