5 Kroner Heilmann type I

Gerhard Heilmann was primarily known as an ornithologist — his 1926 book on the origin of birds remains a landmark in paleontology — and his work for Nationalbanken represents a rare crossover into applied graphic arts. The designs he produced for this series were considered sufficiently successful that the basic type remained in service across nearly two decades, an unusually long run for Danish paper currency of the period.

The dual-signature variants under Lange reflect a mid-series change in bank administration: Lund preceded Bruhn as co-signatory, making series D notes attributable to a fairly narrow window in the early 1920s.