10 Gulden Willem I - Molen

The Molen series was produced by De La Rue in London because Dutch printing infrastructure had not yet fully recovered from the wartime German occupation — the bank relied on British contractors for several postwar issues through the late 1940s. Over twelve million of these notes were printed, a substantial run, yet the series has a relatively short effective circulation window; it was superseded as the bank modernized its note designs through the early 1950s.

Willem I's association with the Dutch financial system gave the series its popular name. The watermark remains the sole security feature — modest even by the standards of the period.