This Cortebert “Extra” pocket watch, designated as a General Service Timepiece, is housed in a soft alloy screw-back case; this example is marked on the back with the broad arrow, “G.S.T.P.”, and “T7905”. Made by Cortebert circa 1942, the signed caliber 526 movement is also marked “15 Rubies”. This movement bears a striking resemblance to the Rolex military pocket watch movement – unsurprisingly, as Cortbert supplied ebauches to Rolex based on the caliber 526 movement. Although superficially the connecting bridge work follows a different layout, all the working parts are interchangeable between the two models.
