Has the original number 1 gold Swan nib
Imprint of "Swan" on feed and imprint of "SWAN M1" on section - see photos
Clear imprint on barrel and the text "SM100/86"
Ink sac and lever work, tested with water
Possible date, late thirties.
Cap has become a bit discoloured possibly due to lying in the sun too long.
Length capped 12.5 cm (4 17/18 inches)
Returns are accepted if you think the pen is not presented clearly in the photos or my description is inaccurate.