Lads from the smoke go up the country to nick red diesel from farm storage tanks.
They put the name of a bogus fuel company on their vans just in case they're stopped, and asked why they have barrels of diesel on board. (We're just delivering fuel, honest guv).
The problem was the lads were not aware of the current geo-political situation, or that diesel fuel is a constituent part in bomb making.
Cat litter is used as a filter to remove red dye from industrial diesel and may well have also been in the vans.
Large bags of cat litter look like the fertiliser that is also another bomb making material.
Some might say "Would fuel thieves travel that far to rob a bit of red diesel though?"
I say "I don't think the transport costs would be an issue."