The Simplo Filler Pen Co decided to market the Montblanc name as a brand product early in the company's history. However, many retailers wanted to carry their own exclusive brand rather than promote the Simplo, Rouge et Noir and Montblanc models and so Simplo pens often reached the customer disguised as a shop brand with a slightly different name or appearance during the firm's first decade or so of manufacture.
The establishment of Excelsior Füllhalterwerke in 1913 as a wholly owned subsidiary of Simplo concealed from the public the direct link between Montblanc and these 'own' brands, enabling the supply of a large number of Simplo products under numerous different names including Diplomat, Reflex and Monte Rosa.
This pen is part of the Diplomat range of safety-fillers, a 'sub brand' that proved especially durable with manufacture continuing until 1928, long after Excelsior had ceased to exist. Pens were offered with both Warranted and Simplo nibs, but not all carried the Diplomat barrel imprint as many of Simplo's customers, including Faber-Castell, purchased pens with no name, added their own brand name and used them to supplement their own product range.
The 'giant' size of this model is especially rare and was the largest of the Diplomat range; it has survived in a remarkably good condition.