I am sure that this thread has run its course as much as the OP intended so I am going to unashamedly hijack it! Keeping with the Dutch theme ...
The man who introduced Kawaishi judo and jiu jitsu to NZ was taught by Jaap Neuwelaerts de Age at the CIOS. Now, I have read your view, Johan, that there is no lasting evidence that the jiu jitsu taught in the Netherlands came from Kawaishi. Considering jiu jitsu only, I have four questions:
1. Who do you think had the greatest influence, technique-wise, on pre-1960s Dutch jiu-jitsu?
2. Who do you suppose had the greatest influence on de Age?
3. In most of the well-known clubs, roughly what percentage of time was spend on jiu jitsu v judo (1945-1960)?
4. Was jiu jitsu taught throughout the kyu grades or was it introduced at a higher level?