Otto Dillenius was an enthusiastic Dutch driver and one of the first in mainland Europe to acquire a Cooper Mk III in 1950. Sadly we know little about him as he died in late 1951.
Some results for Otto:
Mons, Belgium 14th May 1950, 3rd to Harry Schell and Bill Aston
Rouen les Essarts, France 30th July 1950, 6th
Zandvoort, Holland 10th June 1951, 1st
Nürburgring, Germany 29th July 1951 Grand Prix, 8th
Freiburg, Germany 5th August 1951, 7th
Grenzlandring, Germany 9th September 1951, 10th
If anyone has more details, please get in touch.