Tony Williams–What I am going to say next, in light of my warning in my previous post, may seem strange.
I have 2 cabinets ( an 8 drawer and a 12 drawer) similar to the Bisley ones you mentioned. they have drawers that measure 9 x 11 x 3 1/4 inches. Obviously they are deeper than needed for most cartridges. I made trays of wood to fit inside. I can stack 3 trays in each drawer, thus tripling my storage.
I don’t know what species of trees are commonly used in England for lumber, but here in the U.S. it is commonly Douglas Fir, White Pine, Red Pine, Yellow Pine and Ash. With the exception of the Red and Yellow Pine, the others are low in resin. I have used trays made from the others for 30 years with no damage to my lead bullets.
Here is how I make the trays. Again, I do not know the dimensions of lumber in England, but here in the U.S. a 1 inch plank is actually 3/4 inch thick. I start with a length of 1 x 12 plank and rip 1/4 inch thick pieces off the edge so I end up with strips 3/4 x 1/4 inch. I then nail together a frame of a size to fit my drawers. For the bottom I use 1/8 inch paneling normally used on walls and comes in 4 foot x 8 foot panels. I end up with a tray 7/8 inch deep (outside dimension). I use some small nylon cord with knots tied in each end and staple it in place on each end of the tray to act as lifters to remove the trays from the drawers.
For larger cartridges (12 ga., 20mm, 22 boxes, etc. I use 1/4 inch strips cut off the sides of 2 (actually 1 1/2 inch) x 10’s to make the trays. I can get 2 of these in each drawer.