Escaped from Poland in 1939 through Hungary, Yugoslavia and Italy to France (Paris) where he worked as engineer in military industry.

Then, when France collapsed in June 1940, he escaped again, with his family, travelling to North Africa and then by ship to England.

The slip device was modified for use in the Lancasters of 9, 12 and 617 Squadrons of the Royal Air Force for the use of Grand Slam and Tallboy giant aerial bombs.

The Ministry claimed the device was invented at the Royal Aircraft Establishment, Farnborough and developed by Vickers Armstrongs.

The basis of the family claim was a letter written to the Ministry of Aircraft Production by Władysław Świątecki in 1944, just before he died.