Fuller’s earth is a fine clay material that is used to absorb oil, grease and most particularly in a military context chemical warfare agents. The clay absorbs liquids and so is issued to soldiers in small puffer bottles to allow personal decontamination. Individuals are of course not the only things that might need decontamination on the battlefield after a chemical attack, with vehicles and weapons also needing treatment. In the case of these items of equipment, the small puffer bottle of Fuller’s earth would not be sufficient, so larger pouches of the clay are available and today we are looking at a large British Army bag designed to carry this decontaminant:
The contents of this large green bag are easily seen from the white lettering stencilled to the front of the bag:
A large zip is fitted across the back of the pouch to allow its contents to be added or removed:
A pair of fastex clips are attached to the top edge and a strip of Velcro is sewn across the front, presumably to allow the bag to be safely stowed:
I have been unable to determine exactly in what context this bag would have been used, my best guess is that it was for use inside a vehicle to store the clay ready for it to be used to decontaminate the exterior if it were to be hit by a chemical agent. If you do know more about this item, as always please pop it in the comments below!
Tales from the Supply Depot 
Searching on the part number & description there’s a listing on this manufacturer’s website:
http://www.finegroup.co.uk/products/military/nsn with the full NSN 8340-99-762-1145 and a description of ‘Bag Fuller’s Earth Shelter’
As 8340 is the supply class for tents and tarpaulins it could be that the bag is part of an arrangement for decontamination prior to entry to a large tent possibly installed with colpro, as used by the medical services.
It was probably filled from a bulk supply package like this
https://www.ebay.co.uk/itm/373643965711?hash=item56feea750f:g:jycAAOSwtn9g6E1Q
Thanks Rich, that’s some really good information
Thanks Ed, I think that J.S.F. could be J & S Franklin Ltd who produce military shelters and CBRN colpro.
We used to get it in everything from packages to barrels, I was on response teams for NBC for years and we went through a lot of it in training, there was a large supply in every shelter as well, and you were expected to quite literally cover yourself in it then have it brushed off before entering, I suspect this is where this particular item might have been issued. I don’t see anything to reference scale by but it does seem to be designed to clip to a prepared position so it might have been used in Decon tents, probably at least one on each side of the outer entrance, along with a ‘shuffle pit’ trough to drag your boots through (a kid’s plastic wading pool makes a good substirute for that in a pinch and you can pile other gear in it when it isn’t in use ;))
In each individual respirator pouch you carried at least one ‘mitten’ full of the power and you’d ‘blot-bang-rub’ to remove contaminants. It was messy but it worked.
Regarding the ‘Decontamination Kit, Personal, or DKP, we always got issued a 4-pack of the pads (DKP1) and one puffer bottle (DKP2). Never saw anything like this, though.