I dont know if the following has already been mentioned - but may be of interest, Some time after the discovery of the mass graves - In 1943 the head of the Polish Govt in exile in the UK - General Sikorsky- suffered a similar fate to the recent Polish aircrash when shortly after taking off from Gibralter in a British Liberator his a/c crashed into the Straights of Gibralter.
Rumours have abounded ever since that this was a deliberate assassination - with Russian and even British Government involved - On the basis that the General had become an embarrassment for the British at a time we were seeking to please Stalin.
It is understood that to this day the British Govt are unwilling to release
certain relative documents.