Complex sentence: It was the third British aircraft landing operation in occupied Poland, hence its name MOST III. The pilots were George Culliford, a New Zealander, and Kazimierz Szrajer, a Pole.
Split into simpler sentences: It was the third operation of the British plane landing in an occupied Poland, hence its name. Pilots were George Culliford, a New Zealander, and Kazimierz Szrajer, a Pole.