I am sorry Expat but I fear you may have lost touch with the UK since you have been in Malta (if that is wrong I apologise as that was the implication in another thread) and need to take a bite from the reality sandwich.
You just can not compare the Thames Barrier to snow equipment at LHR, the barrier was built because the threat is there at any time of year. Furthermore the effect of not having that barrier is, loss of life, considerable damage to property and business, far in excess of any delays at LHR through not having enough snow clearing equipment.
You draw a comparison with HEL, sorry but Finland gets tons of the stuff so that is just a silly comparison. You say in the other thread that GLA, EDI and ABZ get the same amount at London, what rubbish. I would expect those places to have sufficent snow clearing equipment relevent to the size of the operation for the very fact they get much more of the stuff that the south of England.
The major problems that cause delays at LHR and LGW is fog and seeing as there has not been a way invented to disperse that yet we are stuck with it. In an ideal world where money is no object then snow clearing equipent to the scale would be available. I would agree with the comment that the weather can be used as an excuse for not doing something but then that applies to all industries not just travel.
So what would you prefer? Investment into security equipment and staff that speeds up your journey or snow equipment? I bet if you were asked this question in August I know what your answer would be and I think I know what other people would say.