The 149 is arguably the most definitive model MB ever made! It has experienced uninterrupted production since its introduction in 1952. Even the 146 took a break in production during the 1960s, but not the 149. This celluloid version is known by collectors as 'silver rings' because the pen's cap has two thin silver rings with a gold band in between, just like the 139 which it replaced. Mine has an 18c nib, unlike the more common 14c nib. Maybe it was made for the French market where any items advertised as "gold" necessarily required to be at least 18k gold (even though 14k gold seemed to be the proven ideal material for nibs). An old catalogue from the 1960s describes the pen as having "continental styling" and being "the longtime favourite of the discriminating donor", whatever that means. Further, the pen was positioned as "ideal for doctors, lawyers, engineers, and other professional men". Also, it was "perfectly balanced to eliminate writers' cramp", and "ruggedly built to fill a man's grip and take a man's handling"."
Look at the lovely extra long tines on the nib, allowing for some softness while writing. It makes you feel like you are writing with a precision instrument of some kind! An old catalogue promised that the pen, if armed with an extra fine nib, would "write over a mile without refilling". I date this pen to the mid-50s considering it has the short ink window. (not the earlier medium-sized ink windows) but still has the earlier ski slope feed and cork seal for the piston (instead of plastic).
An interesting fact about the old 149s is that the inner part of their cap top was often made in green striated celluloid - what is today considered a super valuable material. The rest of the pen was only made in black though.
Just like the 146, the 149 has been through many design iterations. First, the material - it started with the prized celluloid in the 1950s but then switched to resin from the 1960s. The telescopic piston evolved into the modern piston and changed from plastic threads in the 1960s to brass threads thereafter (see pic on right). This affects the balance and weight of the pen.
Just like with the 146, Montblanc decided that 'bigger was better' and so the 149 has grown in length over time, as is apparent in the picture to the right. The topmost pic is the celluloid 149 from the 1950s, in the middle is the 1960s resin body 149, and the bottommost pic shows a modern 1990s 149.
The feed on the 149 changed over time too - starting with the "ski slope" style in the early 149s, then moving to iterations of ebonite feeds, and finally settling with modern plastic feeds. The picture on the right shows these feeds in chronological order from left to right. Collectors tend to romanticise the performance of the ebonite feeds over plastic feeds, though I have never been able to tell the difference. My favourite, however, is the ski slope feed.
Rösler, J., & Wallrafen, S. (2001). Collectible Stars: Montblanc-Schreibgeräte von 1946 bis 1979.