So why did he change his name?
Because as many Britiish can pronounce Matyjaszek as there are Poles who can pronounce Threaplethwaite or Cholmondely.
Not unusual for work reasons regardless of the countries/nationalities involved. In politics too. The mayor of my city was from Poland but had an English surname.
Can you imagine some small town folks many years ago choosing the one name on the ballot paper that they can't pronounce?
An interesting guy who certainly knows more
This is certainly true, however a far as pompous and conceited goes, he's off the scale.