From some recent postings overweight seafood as a cause would almost appear to be hardening from conjecture into fact.
That's probably because there's nothing much else in the way of fact to discuss. It may be the easiest reason to pursue and may yet turn out to be cause. But focussing on this now is wrong because it rather gossiply assumes the loadmaster was totally derelict in his duties, either turning a blind eye to gross overloading at the last loading airport or winking at what he thought was normal slight underdeclaring.
Again, that may have been the case. But SleepingFreightDog's post is a good reminder of professionalism.
Say you start from a different assumption. First, that MK are a professional outfit and, despite all the references here to pushing their crews, they actually pay salaries and can attract competent people, inlcuding loadmasters.
Then, that loadmaster jobs, demanding as they may be, are not exactly abundant and, thus, still something people compete for.
If you accept that, you would also have to accept that the loadmaster on this aircraft was a professional and, in a competitive environment, concerned with doing a good job - and keeping it. It's not just his own job - and life - on the line, so one could also assume the rest of the crew he works and flies with is as concerned with how he plays his part as he is with how they do.
There are umpteen ways any person experienced with moving cargo about sees and feels discrepancies; it's a job that fine-hones suspicion and develops a keen sense of exactly where to look for fake info. He would be watching flts lifting the cargo, listening for the load on their hydraulic systems, hefting some boxes from the pallets himself, watching pallets roll and seeing how much effort it took shove them into position, checking as much as he could. Always suspicious. He would probably have loaded the same cargo on previous flights and, if he hadn't, would likely be twice as cautious.
I find it very difficult to conceive that any experienced loadmaster, in a competitive company, with a professional flight crew looking over his shoulder and checking his figures, knowing they were close to maxing out, could possibly have been other than very concerned at the accuracy of declared weights on the last cargo they were taking on board prior to a long flight out of a relatively tight runway. So don't shortchange the man.