Drs. Kees (Cornelis Leendert) van der Leer studied economics and deepens as residents of Voorburg country seat "in de wereld is veel Gevaer 'in the history of ancient manors and other historic buildings. He was co-founder and board member of the Historical Society Zwijndrecht (CVD) and the Historical Society Voorburg (HVV). He is co-editor of Historical Voorburg, the periodical of the HVV and Swindregt Were, the periodical of the CVD and the Historical Society HI Ambacht.
Kees van der Leer has written many books on history and investigated. He also gives lectures. His website is frequently geraadpleegt.