Longines Greenwich Civil Time Navigation Pocket Watch Circa 1940

Brand: Longines
Model: Greenwich Civil Time (G.C.T.) navigation pocket watch
Year: Circa 1940
Case material: Stainless steel
Diameter: 53 mm
Dial: Matte silver 24-hour dial with power-reserve indication
Movement: Manual-winding Longines calibre 21.29
Jewels: 21
Functions: 24-hour display, centre seconds, power-reserve indication
Signatures: Case, dial, and movement signed Longines

A rare and highly purposeful Longines G.C.T. navigation pocket watch, dating to circa 1940 and preserved in the sober, utilitarian language of wartime precision instruments. Cased in stainless steel and measuring 53 mm in diameter, it features the highly distinctive matte silver 24-hour dial associated with Greenwich Civil Time, with outer minute track, blued hands, and an up/down power-reserve indication beneath 12 o’clock.

At its heart is the manual-winding Longines calibre 21.29, a high-grade 21-jewel precision movement with indirect centre seconds, adjustment to temperature and five positions, Breguet balance spring, and micrometric regulation. More than a simple pocket-watch calibre, the 21.29 belongs to Longines’ important chronometric tradition and is closely associated with navigation, deck, and military timing instruments of the period.

The appeal of this watch lies in its clarity of purpose. The 24-hour G.C.T. display was conceived for exact reading in navigational use, where legibility and synchronization were essential. As such, it stands apart from conventional civilian pocket watches, offering a far more specialized and historically resonant expression of Longines watchmaking.

A compelling object for collectors of military, aviation, and scientific horology, this circa 1940 G.C.T. pocket watch brings together technical seriousness, understated design, and one of the most interesting precision calibres used by Longines in the era.

About calibre 21.29
The Longines calibre 21.29 is a manual-winding precision pocket-watch movement used in navigation and deck-watch contexts during the late 1930s and 1940s. Period descriptions identify it as a 21-jewel movement with indirect centre seconds, adjustment to temperature and five positions, lever escapement, self-compensating Breguet balance spring, and combination cam with swan-neck micrometer regulator. Its use in G.C.T. navigation watches places it within the more technical side of Longines production, where chronometric performance and exact synchronization were of primary importance.