To smoke a salmon

This originates from Alan Carrick Smith, Country Life, Feb 1966, abridged by me to save typing ! Note that I haven't tried this myself. I don't even like fish ... but I presume it will work for other things. A muntjac, perhaps ?  I think I can picture the arrangement of the trench/boards/box, but you may need to use your imagination to interpret the description..

Clean the fish, removing as much blood from the backbone as possible.  Make brine by putting one potato in enough tepid water to cover the fish (but don't put the fish in yet), then add salt (4-7 lb) until the potato floats. Immerse the fish for 15-20 hours.  Remove and wash with cold water.  With a pointed knife remove the tail and head, leaving the firm bone by the gills; then split
the fish, remove backbone, fins and any stray bones.

Smother the two sides in soft brown sugar (1-1.5 lb) and plenty of salt. If the fish is large, make nicks along the deep part of the back and push in a little more salt.  Leave on a platter or slab for 12-15 hours.

To smoke: make a trench 30cm x 30cm x 3m long, pointing in the line of the prevailing wind. Take a rectangular box, open on one long side, which will be  broad and long enough to hang the two sides of the salmon from two hooks which have been placed in the inside top. Bore a small hole in the top to aid the draught, or raise one of the boards with a chisel.  Place the box upright in the far end (downwind) of the trench with its open side facing up the trench.  Light a small fire with any wood at the near end of the trench. When this has died down to glowing embers, place a mall barrowload or sack of oak chips or hardwood sawdust along the trench so that the near end will catch from the fire and start to smoke.  Make sure the chips are smoldering really well then place corrugated iron or heat-proof boards over the trench, covering any gaps from which smoke can escape.  Then check that smoke is moving along the channel and up through the box.

Wash the fish, pass strong string through the sholder bones, and hang them in the box. Cover the front of the box with a sack, and check again that smoke is moving freely through the box. leave for 12-15 hours.  Watch the chips from time to time - it there is too much draught they will turn red and give too much smoke, in which case seal off the end of the trench for a time with
sacking or boards.  If the draught is too little, use a board or dig a small trench to convey air through the tunnel more quickly.  A steady gentle smoke is better than a hot cloud.  If the chips are still smoking after 12-15 hours, leave them to go out - this does no harm and will help the fish keep longer.

Hang the sides in a larder, don't refrigerate or freeze unless you absolutely have to.

I don't know much about smoking but have always fancied giving it a go especially as I do my own bacon & ham. A dear, departed friend of mine made a very successful smoker from a filing cabinet but I presume that would be hot smoking as the fire was in the bottom drawer. Is this trench method cold smoking? I've seen a method where the fire is in a pit & a long length of flue liner takes the smoke to the box with the food in it so the smoke is cold by the time it reaches the food.

I guess the smoke would be fairly cool, especially if the woodchips are distributed mostly toward the end of the trench away from the box. And I guess that a filing cabinet might do as the "box".

Somehow the image of a filing cabinet with smoke billowing from every gap has more appeal than it should. Never much liked paperwork ...