Gammeltoft, being an outstanding organizer and merchant, helped the young company successfully through the crisis years for the sugar industry.

His strategy during World War I secured Denmark easier and cheaper access to sugar than any other market in Europe.

[2] Gammeltoft was a specialist judge at the Maritime and Commercial Court (Sø- og Handelsretten) from 1893 to 1910.

He was a chairman of the insurance companies Forsikrings A/S Nye Danske af 1864 and Reassuranceforeningen and of the glass factory Kastrup Glasværk.

[3] Gammeltoft is one of the businessmen depicted in Peder Severin Krøyer's monumental 1895 group portrait painting From Copenhagen Stock Exchange in Børsen.