According to the Archives of Montres Longines, the present competition chronometer was manufactured in 1960. Based on the presence of black markers applied to the subsidiary seconds dial, used during chronometer precision testing, it most certainly participated at a Neuchâtel Observatory chronometer contest where it was awarded a Bulletin de Marche.
Calibre L360, such as the present lot, was launched in 1959 and is known as the "observatory calibre". This highly precise wristwatch movement won in its time the greatest number of distinctions at timing contests.
The model is prominently described and illustrated in Longines Watches by John Goldberger, p. 236-237. For another example of a calibre 360 Observatory movement see Longines by Daria Marozzi & Gianluigi Toselli, p. 25.
For a note on Longines see the previous lot.