Seems very odd that they refer to steel ISO containers which almost every company use, as neither the BPA or EIG or HSE have stated they consider them unfit for use. If you go back to the Firework Co. explosion at Uffculme some years ago the HSE tried to recreate the same explosion with the same quantities and class of fireworks as was supposedly stored, and all it did was blow the doors off.
We can only assume they were allegedly overweight for hazard types stored, which may possibly be a reason why it exploded the way it did, but it seems wrong to imply the use of steel containers as not fit for purpose, when clearly under present laws and MSER 2005 they have not been shown to be otherwise, just correct weight limits per hazard division and safe distances observed. Might be some questions about preraration areas and distances between storage areas, and ensuring strorage areas are always closed prior to any type of preparatory work is carried out even at distance.
As said, interesting to see what the facts were and the possible implications for further modifying MSER if the current limitations are not seen as effective.
Such a sad case for everyone concerned and hope it is wrapped up speedily and fairly.