Adriaan A. van der Willigen explained

Adriaan Marie Anne van der Willigen (26 February 1910, The Hague – 29 May 1986, The Hague)^[1] was a Dutch philatelist who was added to the Roll of Distinguished Philatelists in 1973. He had a master's degree in economics and was a civil servant at the Ministry of Economic Affairs.^[2]

Notes and References

1. Background notes on The Roll of Distinguished Philatelists September 2011, Roll of Distinguished Philatelists Trust, London, 2011. Archived here.
2. https://www.knbf.nl/uploads/pdf/costerus-kapittel/willigen-intro.pdf Adriaan Marie Anne van der Willigen